Hi everybody. I was wondering if anyone out there could explain to me the differences between the c4, c5, and c6 trannies. I have a 1982 F-100 with a 4.2L/255ci motor, which had a c5 for original equipment but now has a c4. I know that these are all 3 speeds with no overdrive, and that the c5 has a different fluid pickup than the c4. I've been told that the c6 is a heavy duty version of the other two. Is the c6 much heavier? My truck was only rated at about 115 HP when it was new, I'd say a fair estimate is 100-105 right now. It's never gonna be anything really fast or special, mostly just a good-looking daily driver -- so I'm thinking that a c6 may be overkill.

Any suggestions? Thanks in advance!!

 

A C5 is a C4 with a lockup torque converter. A C6 is a larger version of the C4. It is quite a bit stronger, but you don't need that with a 4.2L.

 

What is a lockup torque converter and what does it do? Thanks for the speedy reply!