I have two 351M/400 engines for my 77 pickup. (Not sure exactly what they are) one is original, but needs rebuilt. The other has been rebuilt and is in good shape and has some stuff done to it (based on the guy I got it from) whatever that is, I'm not sure. No brained there.....but I found a 390GT out of a 68 Ford torino GT. It is now in a tow truck. Motor has about 50k on it. Doesn't smoke, runs good for 300 bucks. Question is...should I buy the 390 or use the 351M/400?

 

Are they 351m. Or 400's check

 

300 for engine plus another 700 to get it to work in your truck if you need to buy other parts.

 

I would tear each one all the way down and rebuild one if you have the time and money. That way you know what you've got to work with and who has done all of the work.

 

How much has to change to get the 390 to fit? I've always heard that the 390 is a far superior performing engine.

 

Personally I really like the FE engines but that doesn't matter.
To switch from a 351M-400 depending on the transmission you have. If you have a C6, you'll need to get a different transmission. FE's and 351M-400 have different bolt patterns and don't interchange. The C6 has an integral bell housing and you'll have to switch the complete transmission. If you have a manual trans., you'll need to get a different bell housing and flywheel.
All of the accessory brackets will need to be changed (alternator, power steering pump, A/C, etc.) motor mounts and towers etc.
Unless you really like the 390, I'd stay with the 351M or 400, whichever one it is.

 

I'd build a'low buck 460... $2500 will garner about 400 hp of low rpm, stump pulling power... and ya know what's in it by your own hands.

 

Would love to but I don't have a 460 on hand and I'm trying to not have to do any rebuilding........for now.

 

Keep it simple, use the one that's been rebuilt.

 

you know the history of your trans? if you feel comfortable with it id keep the good engine you have and run it
( after few simple tests to verify its good )

 

run the supposed rebuild and while you are running that one put the other one on the motor stand and rebuild that one the way you want, you can take your time and when the time comes and you either blow the other motor or just finish rebuilding it you can swap them. i wouldn't mess around with forcing a supposed fresh 390 into the truck when you can take that money and rebuild a drop in.