Engine decode confusion
 

this is not a question about a f-body
and i am sorry to bring this off forum question to ya'lls board but im confused and ive been lurking around reading post from ya'll for a few weeks and liked how knowledgeable the members were so i thought i might as well ask ya'll

ok i just bought a 97 s10 with a 350 swap, couldnt find a f-body to suit me:(, i have been trying to figure out some things about the engine b/c the seller didnt know much about it.

all right i have found a few stamps and they are
-5.7lg on back flange near bell housing
-casting #-10054727 also on back near bell housing
^both on drivers side
-K0803UKA stamped on pass. side under alternator by the waterpump

ok here is where i became confused

the casting # tells me this-10054727...350...86-up...2 or 4 bolt...one piece rear seal, some "Made in Canada"

but the front "ID code" tells me this
K0803UKA-
K=St. Catherines, Ontario(McKinnon Industries Canada)
0803=Aug. 3rd.
UKA=1981,350,con. cab, m/t, A.I.R.,P LF5,150hp,2 BBLS,BODY C-30 & 3500,159.5WB
Addition info-center bolt heads, and the spot where a mechanical fuel pump would go is there but its about 1 inch or more deep then solid.

i am confused because the casting # states 86 and up but the sufix code shows 1981, but a 1981 wouldnt have had center bolt heads and would have used a mechanical fuel pump right? any input to help me clear up this is greatly appreciated.

THANKS GUYS

Hello guys posted this on a couple of sites and found the answer i was looking for, if any one is also having trouble her is a good site to use

Chevymania Casting and Suffix Tables