I just got a 78 Bronco that has a 351m, C6,205 t-case. I have been out of the engine swap arena for 20 plus years, so here is my question if you do not mind. I love the 300 six...my favorite motor of all time. Will the 300 bolt up to the C-6 thats in the Bronco? I am guessing no since the 351m is a big block pattern? Hopefully I get good news as I would love to build a 300-6 and put in this bronco

 

Correct, the small block pattern is what is needed.

 

How common was the 300/C-6 combo in a 4x4? Is there and adapter made to go SB to BB pattern?

 

Small block 4x4 C6's are pretty easy to find. Look for them in 1980+ Fullsize trucks and Bronco's. They came behind 300's, 302's and 351W's. And Ford built a whole lot of them in the 80+ 4x4's. Look at the engine and if it's one of them I mentioned above then look at the shift indicator. If there is no circle around the "D" it's a C6.


You will also need to do something with the motor mount frame perches/towers. The 300 takes a different tower/perch. If you want to replace them you'll need to find a pair out of a 78 or 79 F150 4x4 with a 300. And that will be harder to find then the C6 will be. The other/easier option is to just modify the stock 351M/400 perches. I'm not sure what would be required. You'll have to drop the engine in and see how it will sit and what will need to be modified.