dose the ''y'' stand for 350 engine or 454 engine...my first 3 number, letters are ccy i beleave the cc is chevy, 2 wheel drive. but i have seen a couple diffrent one's for the letter ''y''...like it means's 350 and on another site say's 454 ''p'' model never herd of a ''p'' model 454.... any-body know what it mean's.

73-75 Y=350

I use this guide:
http://www.lmctruck.com/icatalog/cc/full.aspx?Page=12

thank you for that info ''School Fire''