help with ECM and prom

[WATCHmeDRV at aol.com]

I have a 88 Vette with 1227165 it has been upgraded to a 16198259 the prom 
that was in it is ABTR4763 and I had a GM dealer order me a new prom so I 
would have one to play with the programming, I thought it would be the same 
numbers on the proms but the new prom # is ABTR4762. The new prom which is 
supposed to be the same as the old prom at least that's what the dealer told 
me, runs better than the old prom. I am lost has anyone worked with this PROM 
or do you know anything about the prom #'s. The new prom runs fine I'd just 
like to change the temp settings. There was someone here that had mastertune 
for an 87 Vette with the 4+3 trans as for as I know it is the same as my 88 
with the 4+3 trans. Would you send me a file to try from the 87. I run a 160 
stat. some the fans at on at 185 and off at 175 is good.
thanks 
AMERSON