s10 engine question
 

i have a 1985 S10 blazer 4x4 and it has a newer model 4.3 engine with
throttle body and 2 injectors ,,the problem is i dont know the year of
the engine ..this number is stamped on the rear GM2134225 i cant tell
for sure if the last digit is 5 or a S, can any one tell me the year of
the engine or mail me a website to find out?? =A0 thanks for any help