what is the different between a b17 gsr head and a b18c1 and how you know what year is the head but there some numbers on the head can't figure out what year is it

 

there are two b-series vtec heads, there is the pr3 and the p72

The PR3 comes on all VTEC B-series engines, minus the 3rd generation GS-R (though i do believe the JDM sir-g has the same P72 head as the 3rd gen)

the P72 is on the 94-01 GS-R, it has smaller combustion chambers and provides higher compression, it also gives better flow numbers than a p72, with the exception of a head that comes ported stock (such as the Type-R's PR-3)

in most cases the P72 is the more desireable head. it has the most potential and in most cases is already better than the PR3

in your case, the b17 head is a pr3, and the b18c1 head is a p72.

 

quick question which head is the most desireable for a ls/v i have heard both and was wondering which one and why

 

the p72.

but let it be known that you will need to upgrade the rotating assembly to have a motor that withstand the high-rpm's needed to make power with a vtec head. you can't simply just put the head on there and expect everything to be good