I have a 76 f150 2wd. With a 300 I bought a late 70s Ford van with a 351 c6. My question is will the c6 bolt up to the 300 with the 351 flex plate? If not please give me pointers on the swap. I'm a v8 guy wanting to build a 300 with a bit of power adders. Thanks

 

There's one very important piece of info missing that will be the deciding factor between yes and no.

Is the 351 a 351m? Or is it a 351 Windsor? Judging by the year, I'm assuming the 351m, but I don't know when they started putting Windsors into the vans.

If it's a 351w, the answer is yes.
If it's a 351m, the answer is no.


The 351m is a big block and has a big block bolt pattern and matching transmission. There is simply no swapping anything over to the 300.

The 351w is a small block and shares the same bolt pattern as the 300 and 302, so the transmission will bolt right up to the 300 like it was made for it. You'd probably need a different flex plate since the 300 is zero balanced but that's about it.

 

Here's how to tell if it will fit your 300. Look at the front of the transmission. Then Measure the distance between the top two bellhousing mounting holes. If they measure 5 1/8" then it will fit. If they measure 7 3/4" then it won't fit.




Most 70's vans with 351's were 351W's. You didn't see much of the 351M/400's in vans until the 79-81 year range.

The 351W flexplate won't work without having it re-balalnced. And it's usually cheaper to just buy a new 300 flexplate. If you run the 351W flexplate you will have a major vibration. Does your 300 currently have a flexplate on it? If it does run that. If it had a manual transmission then you will need to buy a 300 flexplate ( 164 tooth, 0 imbalance ) .


Also don't forget to install the block spacer plate.

 

Thank you both for the answers. Yea I was a dumb a%* and not verify it is a 351w. I will buy a flex plate for the 300.