GMC Repair: 87 r3500 truck w/ 5.7 tbi ecm question, full proof, fuel pump

Question
I have an 87 r3500 w/ 5.7 tbi and manual trans.
I have a friend that helped me narrow my problem to what should be the ecm.  I wanted to pick one up at the junkyard but I was wondering if other ecm's are interchangeable.  It seems that i've found that the part number for the ecm is supposed to be 1227747 but i noticed that in some listings the number is followed with some letters.  Can I use any ecm that has the numbers 1227747 as long as I use the old prom? And what are the chances that the prom could be bad?
thank you,
Sean
p.s. just so you know why we think this: The truck was running okay but the fuel would slowly cut off to the engine and every time i shut off and restarted the engine it would run ok again for another few minutes. It was also blowing ecmb fuses. We put a jumper on the relay to the fuel pump which my friend told me makes it bypass the relay and ecm. So with the jumper keeping the fuel pump running then the truck ran fine. That makes him think that it's the ecm because he says that relays are usually pretty full proof. Let me know your opinion.

Answer
Hi,Sean.

 Yes you can use another ECM as long as the part numbers are the same,you need to swap the proms over they are not interchangable,i have heard of proms being bad but very rarely,i was reading your complaint and though your ecm fuse is shorting i would lean more towards a failed/shorted fuel pump,the fuel pump on your truck uses the same fuse as the ecm does,if the fuel pump is failing it draws to much current/amps causing the fuse to blow or go open,i would really check your fuel pump,i think this may be the problem your having.if you need more help feel free to contact me.Thanks

ED