I don't know if my transmission is out of the 80-81 an could of been mix matched over the years since it has a 351w in it...
but question is its a 4 speed manual but is there anyway of telling what size clutch it takes without taking it out I know there's a 10 inch an a 11 inch clutch

thanks

 

go online to LMC truck and check out the catalog, it shows bolt patterns to help you figure out which tranny you have....I have a 85 f250 302 efi with 4 speed with granny gear....it has a 10 inch clutch....hope this helps

 

If you have a 351W then the engine has been swapped as it should have had a 351M from the factory. And, since those two engines have different bell housing patterns then at least the bell housing was swapped as well. But, it still could be the same tranny. A granny low 4 speed would most likely be the NP435.

 

As Gary mentioned, an NP435 is probably the most likely granny low option, or a T18........but the 80-86 transmissions all had the same input shaft dimensions & splines......so knowing the trans your truck has, won't help you confirm the plate diameter.

Can you order both kits, & return one, to cut out downtime?