transmission

[scottlogger]

i have a 400 in my 69 with a c 6 trans what other auto trans can i use in place of the c6 without a lot of massave changes thanks for the help

[HIO Silver]

Is budget a consideration? Or just effort?

High cost = easier to do
Lower cost = more effort required on your part

Why do want to go get rid of the C6?

[mmerlinn]

i have a 400 in my 69 with a c 6 trans what other auto trans can i use in place of the c6 without a lot of massave changes thanks for the help

Only "easy" possibilities are FMX or C4 with dipstick in the pan. C4s with dipsticks in the case will NOT fit.

Pros and cons:

FMX near bullet proof from the factory with few aftermarket mods available. C4 can be upgraded with aftermarket parts to withstand lots of HP.

FMX and C4 both have factory bell housings available to fit your motor. Neither are real easy to find, but C4 is most expensive.

FMX deadweight is more than the C6. C4 is very small and light.

Both the FMX and the C4 have less parasitic drag than the C6, with the FMX having the least.

C4 has the least rotating mass with the FMX next and C6 with the highest.

C4 will put the most HP to the tires. Not sure whether FMX or C6 is next as the additional deadweight of the FMX may offset the additional parasitic drag of the C6.

FMX cores are much easier and cheaper to find than C4 cores.

FMXs to fit your motor were made from 1969 to about 1981. C4s from 1975 thru 1979.

Any FMX (68-about 81) and any C4 with dipstick in the pan (65-79) will fit by changing the bell housing. In addition there are a few C5s (82-86) that will fit by changing the valve body, bell housing, and converter.

Unless you can find a donor vehicle, neither are a bolt and go replacement for the C6 as many things need to be changed.

All of the above applies ONLY to rear wheel drive applications. 4x4s are a different can of worms.