Sunset Venery has posted an optimum Gearbox Design for most of the 3-output gearboxes on this list, including the cost of the metal. The form of the indicated cost is (build <medium+6*large>m<units of metal>). Understanding the relative value of the various gearboxes will help you make a fair exchange.
When you're looking for a suitable gearbox, keep in mind that a multi-output gearbox can be used in place of a single or double output gearbox. For example: C400 G200 can be used for a C400. If you only need a single or double output gearbox, the Ctl+F find function is a very effective way of finding an appropriate gearbox that will satisfy your requirements, and the Wiki search function is also excellent.
| a100 b100 c100 (build 0m20) | Saqqara Lake Guild, Tokay |
| a100 g167 | OldJoe, Trillian |
| a116 b116 | Tokay |
| a120 e120 h333 (build 3m92) | Gada |
| a120 f240 h120 (build 4m108) | Red Sea Disciples |
| a13 | Alzarus |
| a13 b13 h400 (build 8m190) | Venery |
| a139 b139 f193 | Sallah-Hazerah |
| a139 b139 f463 (build 5m122) | Saqqara Lake Guild |
| a144 d480 f480 (build 6m146) | Red Sea Disciples |
| a144 e173 g173 | Sallah-Hazerah |
| a167 b167 c167 (build 1m40)(installed in nd 716,6469 wt) | Saqqara Lake Guild |
| a167 f400 | OldJoe |
| a167 f69 h69 (build 4m104) | Red Sea Disciples |
| a193 b193 c193 (build 6m134) | Saqqara Lake Guild |
| a193 f536 h536 (build 8m186) | Red Sea Disciples |
| a200 b200 c200 (build 2m58) | Tokay |
| a200 b200 f167 (build 3m80) | Gada |
| a200 b200 g167 (build 3m80) | Red Sea Disciples |
| a200 e167 f167 (build 3m86) | Red Sea Disciples |
| a200 g333 | Sallah-Hazerah |
| a231 h42 | Saqqara Lake Guild |
| a240 | OldJoe, Trillian |
| a240 f240 g240 (build 4m102) | Tokay |
| a240 g252 | Sallah-Hazerah |
| a278 c167 f167 (build 2m68) | Tokay |
| a278 c278 h30 (build 5m120) | Saqqara Lake Guild |
| a278 e463 g386 (build 5m122) | Red Sea Disciples |
| a30 c11 d50 (build 5m122) | Venery |
| a333 | Gemstar, Sallah-Hazerah |
| a333 b333 f100 (build 3m84) | Red Sea Disciples |
| a333 c333 d333 (build 3m78) | Red Sea Disciples |
| a333 c333 f278 (build 4m106) | Saqqara Lake Guild |
| a386 d386 g386 (build 5m128) | Tokay |
| a400 b400 h15 | Sallah-Hazerah |
| a400 b400 h333 (build 5m122) | Saqqara Lake Guild |
| a400 b480 g400 (build 7m158) | Venery |
| a400 c556 e556 (build 6m138) | OldJoe |
| a400 e333 | Sallah-Hazerah |
| a400 f333 g333 (build 5m122) | Tokay |
| a400 g30 | Sallah-Hazerah |
| a463 | Alzarus |
| a463 (2 are available) | Saqqara Lake Guild |
| a463 b463 c463 (build 3m80) | Gada |
| a463 b463 g386 (build 5m132) | Saqqara Lake Guild |
| a463 b463 h116 (build 6m142) | Red Sea Disciples |
| a463 c463 g50 (build 5m130) | Red Sea Disciples |
| a463 f278 | Tokay |
| a463 f463 | Sallah-Hazerah |
| a52 b52 h36 (build 6m142) | Tokay |
| a60 c60 e60 (build 1m44) | Red Sea Disciples |
| a60 c60 f463 (build 4m108) | Tokay |
| a72 | OldJoe |
| a72 f278 g278 (build 5m124) | Gada |
| b100 f167 | OldJoe |
| b120 d120 f120 (build 2m60) | Red Sea Disciples |
| b120 e333 g400 (build 5m122) | Red Sea Disciples |
| b120 f278 h278 (build 4m102) | Red Sea Disciples |
| b13 d400 | Venery |
| b139 c139 d139 (build 3m78)(on loan to sallah) | Saqqara Lake Guild |
| b144 d86 g240 (build 5m126)(in use at 1791, 2578) | OldJoe |
| b144 e144 g288 (build 6m140) | Tokay |
| b144 f288 g288 | Sallah-Hazerah |
| b15 d18 f15 (build 7m146)(in use) | OldJoe |
| b167 h400 | Gemstar |
| b193 c193 f116 (build 6m140) | Red Sea Disciples |
| b200 c200 d200 (build 2m56) | Saqqara Lake Guild |
| b240 c240 d240 (build 4m90)(installed in nd 565,7094 osm) | Saqqara Lake Guild |
| b240 d240 f240 (build 4m94) | Venery |
| b278 | Sallah-Hazerah |
| b278 c278 f278 (build 2m62) | Saqqara Lake Guild |
| b278 d278 f120 (build 4m102) | Saqqara Lake Guild |
| b278 f278 h333 (build 4m100) | Red Sea Disciples |
| b317 c317 g317 (build 10m224) | OldJoe |
| b333 (in use at 2300, 2110) | OldJoe |
| b333 d100 h167 | Elle |
| b333 d333 g278 (build 4m106) | Venery |
| b333 e556 g400 (build 6m144) | Red Sea Disciples |
| b333 g120 | OldJoe |
| b350 g175 | Venery |
| b386 c386 h278 (build 5m126) | Venery |
| b386 d463 e463 (build 5m120) | Red Sea Disciples |
| b386 f278 g278 | Sallah-Hazerah |
| b386 f286 | OldJoe |
| b400 | Sallah-Hazerah |
| b400 c400 g200 (build 4m102) | Rym |
| b400 f167 h167 (build 5m132) | Saqqara Lake Guild |
| b400 f400 | Tokay |
| b400 g333 | Gada |
| b463 | OldJoe |
| b463 c463 d463 (build 2m82) | Saqqara Lake Guild |
| b463 c463 h139 | Sallah-Hazerah |
| b463 d167 h200 (build 5m124) | Gemstar |
| b463 d400 f400 (build 7m164)(in use at 2300, 2110) | OldJoe |
| b463 d463 h167 (build 3m84) | OldJoe |
| b463 f200 | Venery |
| b463 f83 | OldJoe |
| b480 c480 f278 (build 8m180) | Venery |
| b480 f556 | Sallah-Hazerah |
| b50 d60 g400 (build 6m142)(in use) | OldJoe |
| b50 d60 g400 (build ??)(hounddog) | Venery |
| b556 c556 h120 (build 4m110) | Saqqara Lake Guild |
| b556 c556 h463 (build 5m124) | Saqqara Lake Guild |
| b556 d556 g463 (build 5m122) | Red Sea Disciples |
| b60 d60 f60 (build 1m42) | Red Sea Disciples |
| b60 f400 g400 (build 5m122) | Saqqara Lake Guild |
| b60 g463 h463 (build 4m106) | Saqqara Lake Guild |
| b83 d83 h83 | Sallah-Hazerah |
| b96 (2 gearboxes) | Sallah-Hazerah |
| c100 | OldJoe, Tokay, Trillian |
| c116 g231 | Sallah-Hazerah |
| c120 g480 h480 | Sallah-Hazerah |
| c13 f278 h278 (build 6m150) | Red Sea Disciples |
| c139 d139 f463 (build 5m122) | Red Sea Disciples |
| c139 d231 g278 (build 5m124) | Tokay |
| c139 e139 g139 (build 3m80) | Red Sea Disciples |
| c144 d144 f333 (build 5m122) | Red Sea Disciples |
| c167 f100 h100 (build 1m46) | Tokay |
| c200 | Gada |
| c200 d120 g120 (build 2m66) | Red Sea Disciples |
| c200 e120 h120 (build 2m66)(in use) | OldJoe |
| c200 f480 | Saqqara Lake Guild |
| c200 g280 | Gada |
| c22 f278 h278 (build 5m128) | Red Sea Disciples |
| c231 | Gada |
| c231 d231 e231 (build 4m96) | Saqqara Lake Guild |
| c231 d231 h386 (build 5m124) | Red Sea Disciples |
| c240 e240 g240 (build 4m98)(tokay sept. 7) | TpcT |
| c240 f400 g13 (build 9m208) | Tokay |
| c240 g400 | Venery |
| c278 d167 e278 (build 2m62) | Tokay |
| c278 e278 g333 (build 4m98) | Red Sea Disciples |
| c278 f278 h231 (build 4m104) | TpcT |
| c278 f463 h463 (build 3m88) | Red Sea Disciples |
| c322 d463 h463 (build 7m164) | Venery |
| c333 | Sallah-Hazerah |
| c333 f333 h333 (build 3m82)(in use at 1791, 2578) | OldJoe |
| c386 e139 f139 | Sallah-Hazerah |
| c400 | OldJoe, Tokay, Trillian |
| c400 d400 g42 (build 8m178) | OldJoe |
| c400 f36 | OldJoe, Trillian |
| c400 g400 | Gemstar |
| c415 d415 h120 (build 11m238) (installed in nd 737,6358 wt) | Saqqara Lake Guild |
| c42 | Neutron |
| c463 | Sallah-Hazerah |
| c463 d463 e463 (build 3m80) | Saqqara Lake Guild |
| c463 d463 f556 (build 5m118) | Saqqara Lake Guild |
| c463 d463 g50 (build 5m124) | Red Sea Disciples |
| c463 e463 g120 (build 5m126) | Red Sea Disciples |
| c463 e463 h167 (build 3m84) | Red Sea Disciples |
| c463 e463 h231 (build 4m110) | Saqqara Lake Guild |
| c463 f278 h333 (build 5m120) | Saqqara Lake Guild |
| c463 h463 | Sallah-Hazerah |
| c50 d480 g480 (build 9m206) | Tokay |
| c50 g278 | Saqqara Lake Guild |
| c556 | Sallah-Hazerah |
| c556 e240 g144 (build 7m164)(in use) | OldJoe |
| c556 e240 g144 (build ??)(hounddog) | Venery |
| c556 h556 | Tokay |
| c60 e60 g60 (build 1m42) | Red Sea Disciples |
| c83 | Saqqara Lake Guild |
| d120 | Sallah-Hazerah |
| d120 f120 h120 (build 2m60) | TpcT |
| d120 f200 h333 (build 3m82) | Red Sea Disciples |
| d13 e36 f36 (build 4m102) | TpcT |
| d139 f386 h386 (build 5m124) | Saqqara Lake Guild |
| d144 f400 g400 (build 6m134) | Saqqara Lake Guild |
| d161 e161 | Sallah-Hazerah |
| d167 g278 | Sallah-Hazerah |
| d167 g333 | OldJoe, Trillian |
| d167 h556 | Saqqara Lake Guild |
| d193 f231 | Saqqara Lake Guild |
| d200 | Sallah-Hazerah, Saqqara Lake Guild |
| d200 h167 | Venery |
| d22 f22 h22 (build 3m84) | Red Sea Disciples |
| d231 e193 g161 (build 8m196) | Red Sea Disciples |
| d231 f60 | Saqqara Lake Guild |
| d240 e240 g400 (build 4m98) | Red Sea Disciples |
| d240 g400 | Sallah-Hazerah |
| d26 f26 h26 (build 5m118) | Red Sea Disciples |
| d278 f463 h463 (build 3m86) | Red Sea Disciples |
| d288 | Sallah-Hazerah |
| d292 f486 | Sallah-Hazerah |
| d333 h193 | OldJoe, Trillian |
| d386 e278 f278 (build 5m122) | TpcT |
| d386 e386 f386 (build 5m118) | Saqqara Lake Guild |
| d386 f83 g83 | Sallah-Hazerah |
| d400 e400 f69 | Sallah-Hazerah |
| d400 e400 g240 | Venery |
| d400 f400 h400 (build 4m98) | Saqqara Lake Guild |
| d400 g400 h420 (build 10m226) | Tokay |
| d42 f42 g42 (build 4m98) | Red Sea Disciples |
| d463 e463 g120 (build 5m126) | Tokay |
| d463 f193 | Gemstar |
| d463 f386 | OldJoe, Rym |
| d463 g278 | Sallah-Hazerah, Saqqara Lake Guild |
| d556 h167 | Neutron |
| d72 e72 f463 (build 6m148) | Tokay |
| d72 f72 h72 (build 3m78) | Red Sea Disciples, Saqqara Lake Guild |
| d83 e139 f556 (build 7m164) | Tokay |
| d83 f36 h60 (build 4m104) | Red Sea Disciples |
| d86 g30 h25 (build 9m204) | Tokay |
| e116 | Sallah-Hazerah |
| e120 | Sallah-Hazerah |
| e139 | Sallah-Hazerah |
| e139 f139 g139 (build 3m78) | Saqqara Lake Guild |
| e167 f167 h167 (build 1m40) | Saqqara Lake Guild |
| e231 f231 g231 (build 4m100) | Saqqara Lake Guild |
| e333 | Gemstar |
| e333 f333 g333 (build 3m80) | Saqqara Lake Guild |
| e386 f386 g386 (build 5m120) | Red Sea Disciples |
| e463 | Sallah-Hazerah |
| e463 (in use at 2662, 999) | OldJoe |
| e52 f52 h52 (build 6m140) | Tokay |
| f159 | Venery |
| f200 g200 h200 (build 2m56) | Red Sea Disciples |
| f33 | Gemstar |
| f333 | Venery |
| f400 h400 | Saqqara Lake Guild |
| f72 | OldJoe, Trillian |
| g100 | Tokay |
| g139 | OldJoe, Sallah-Hazerah, Trillian |
| g400 | Gemstar |
| g463 | Alzarus |
| g480 | Sallah-Hazerah |
| h544 | Alzarus |