I am considering reverting back to the flathead for my 51 F1. Current engine required the previous owner to do a lot of cutting and pasting that im not too fond of. Will a 1950 flathead fit into the f51 frame? Also, will a 59T 4 speed work with the flathead engine? How far gone is an engine to be considered "too far gone." I'm looking at a flathead starter kit (literally in pieces, and has been setting out in the elements for a while). I am new to this game and my internet searches lead me to more questions. You all have been pretty straight and simple with the answers, so that I appreciate.

 

Any 8BA / 8RT from 48-52 will fit as long as it has the truck motor mounts. Of course depending on what modifications the previous owner made will determine how much work is ahead of you. Post some pictures of the current motor mounts and as much of the frame area around the engine as possible.
59T is actually the case number, it's probably a T9 which is the standard spur gear 4 speed from this truck. Yes, it will hook up to the flathead.
The proposed 'starter kit' sounds like a junk engine that will be a lot of work if even possible to fix, unless you are getting it for about $50 I'd pass till I could find one complet that has not been setting out in the elements.

 

Anything is possible ole story fire axe and a welder and a grinder and
paint. I do not judge books by covers. Example my son bought a
so called froze up V8 for 75 bucks outside but upside down. We rebuild
here and $75 is more needed parts for stock. Come to find out, its a
EAB which I think is the best one. So after disassemble and a good bath
We have a perfect all standard perfect crank, with no cracks.We spent
around $800 new pistons rod main cam bearing adj lifters, new oil pump.
new carb fuel pump one of those alternators looks like a genny. Day of
reckoning ONE turn and running on the test stand. Oh we had a muffler
and tail pipe on it. Smooth as a kitting silent as a cat seeking up to a rat.
My fair guess I'd say total maybe $1100 with the little things wires plugs
oil filter. Also oil pressure 50# cold 45# hot at idle........

 

Harley,
here are some pics of the frame:

 

OMG, you are wise to rid yourself of that awful "construction"!!

Some key pieces for a flathead retrofit are missing (the motor mount supports in particular). Has the transmission crossmember been cut? If so, I would look to install that engine or another modern engine and trans correctly, forget the flathead...

As far as the "kit" goes, you are nearly always better off buying the best you can find, not the cheapest. The kit doesn't sound like the best.

 

Oh Wow !!! I see your concerns. Ross is right about the engine "kit". You will need to be thorough in your inspection of it.

Here is my '50 flathead mounted with Reds Headers. The frame is designed for that engine so you won't have the fitment issues that you have now.