Ok so I removed the 300 6cyl and installed a 302 into my 1970 f100 custom shortbed and having problems with drive train and radiator. The original trans out of the truck was a c-6 and 302 came with a c-4. we bolted up the c-6 to 302 and moved motor mounts back to aft bolt holes....Yea I'm in the navy and use navy terms..lol. We adjusted the trans mount forward but when installing drive shaft it is 2'' short. I called around and i guess in that year there are three joint shafts or two joint shaft that are shorter. From weld to weld mine is 45 1/2'' and I need 47 1/2'' to make it work. Should I just get one made or did they make them in maybe another year? The radiator is my other issue. The original radiator for the 6 has the flow and return on the opposite sides. What year of radiators will fit and work on my 70 with a v8 or 302? The mount holes are from left to right 25 1/2''. Thanks guys

 

Pretty sure the 302 requires different motor perches all together. Did you simply move your I6 perches back or replaced them with the proper ones? You shouldn't have had to move the transmission mount unless you were swapping the tranny as well. I dunno I may be wrong however if you used the lower half of the motor mounts from the I6 your small block probably isn't positioned right.

 

I had a 302/C6 in my '70 & the driveshaft came from a mid '90's Ranger.

 

The C4 is shorter than the C6, so you'll need a different driveshaft. If you have a center support bearing, that's a three joint shaft. The two joint shaft was used primarily on shortbed trucks.
You can get your existing driveshaft retubed for a minimal cost, around here I can get it done for $120-$150. They use your existing ends, grind the weld off, and weld on a new tube of the proper length.
It sounds like you just need a V8 radiator, you need one for a 68-72 or a 73-79 with a front mount, most of the 73-79 used a rear mounting though. I welded brackets in on mine to use a rear mount radiator but it was only because that was the only radiator I had and the top tank on my old one split.

 

He said he bolted the c6 to 302 in which case the transmission wouldn't need to be changed what so ever. With the proper mounts the 302 should bolt right up to the c6 that was in the truck without any modification to the driveline.

 

I keep the same perches in that the 6cyl was mounted to and 302 mounted right in. I did move them back to next bolt hole and trans crossmember came to the forward most holes. So far everything is working perfectly except for driveshaft. I don't think ford made or just didn't put 302 in the truck.. I dunno but that's what I found out. Going to get a driveshaft made and a guy has 4 radiators that I'm going to try and match up. Thank all of you. This is a great site

 

So the c6 trans does mount up with the right spacer plate. Hard to find :/

 

Small blocks use different perches its the Big blocks of that era that share the perches with the I6 you shouldn't have to change the driveshaft to mount a c4 or a c6 considering those were both options in 72 if that transmission was mounted to a 6 it should work for a 302, you should be able to leave the small block c6 right were it is driveline and all and bolt the engine right to it if you swap in the c4 you'd just have to move the crossmember forward. We tossed a roller 302 into the 67 longbed my cousin owns and nothing from the bellhouse back needed to be modded just the engine and parts that go with it. The 300 and the 302 don't use the same perch the perches.


Scroll to the bottom.
https://www.ford-trucks.com/forums/6...ne-mounts.html

 

so should I change the perches or keep the original ones in. The motor sits fine and the trans does line up on the cross member but it is on the forward holes. We crunk it up today for a few min just to get a little accomplishment and no problems. Also if I should change the perches where would a good place to start looking for them at? I found out the carolinaclassics.com: The Leading Carolina Classics Site on the Net has a lot of hard to find parts but not sure if they would have these.

 

I'd swap the perches if it were me, I don't see spending the money modding the driveline when its a simple bolt on part and whos to say you don't mod the driveline and wind up with it a little off and create even more problems.

 

I will see if I can find a pair and compare them to see what is different. Thanks