FMX to C4 Driveshaft Ques.

[56 Aero]

I'm swaping in a C4 302 combo in my 69 SWB. It had a FMX with a 300 I6. The FMX had a slip style output and the C4 is a bolt on. So which do I have to change, the driveshaft or output shaft on the C4. If the driveshaft is the best/only option which year truck would be a good choice for finding a driveshaft with a slip yoke I could cut to fit my shortbed. Thanks in advance guys for your input.......Rick

[FORDification]

Well, you're not gonna like this answer, but the only way you're going to be able to use that transmission in your truck is either to get an expensive custom slip driveshaft made or to go through major surgery to exchange the whole back end of the transmission for one set up for a slip yoke. It's not an easy operation.

To make the custom driveshaft, you'll need the rear driveshaft from a 4x4, which has the built-in slip joint, and get it lengthened to fit.

[56 Aero]

Hmmm, well, dang it! The FMX was abused (run about 2 quarts low on fluid) and it won't shift into 3rd. The C4's fluid looks more like a strawberry milk shake than tranny fluid but it would shift. From what I've read on the forum the FMX is not a popular option, when I found this C4 (free) I snaged it. Well it's off to the junk yard, then a drivshaft shop. Thanks for the info..........any other opnions or input?............Rick

[56 Aero]

OK next question, did any of the C4 trannys come with a slip yoke, or were they all bolt on tail shafts???........Rick

[fordman]

they probably had bothe the slip joint and the slip yoke. i have some driveshafts if you need one. i have either option. including th one in the pic kieth shows. i just found it on a junkyard truck.

[56 Aero]

Thanks Fordman, I've found another 302 with tranny, but I've not seen it yet and the owner don't have a clue which tranny it is. It does have a slip yoke, so he says. I'm going to look for a driveshaft around here, if I can't find one I'll get back to ya. Thanks again for the info..........Rick

[FORDification]

Cars and most SWB trucks had the slip yoke. All LWB trucks have the bolt-on yoke.

[56 Aero]

Thanks Keith, maybe I'll get lucky and this other tranny will be a slip C4.......I have changed the front end to disc brakes and power steering, also found some good doors and fenders so I'm still making progress on the old girl. Thanks again guys for your help...........Rick