Just out of curiosity, where did you find a new Y-pipe (Pre-fabbed, I'm guessing) for a late 70's rig?
I don't THINK there is any difference in the frames ... Maybe with pipe diameter or manifold connection or length/bend of pipe? I really don't know... I'd guess it's the cat connection... Pretty sure no 78' came with a cat (My 79' didn't although all the catalogs say they do...)
Sme 87's had had a small cat in the pipe from the left bank. It varied as to it was heavy duty or light duty and if it was a kalyfurny or 49 state truck. I believe it was to b generate heat to get the main cat up to operating temperature quicker on cold starts. :gr_patrio
i had an 86 w-150 and looked into that myself. parts guys had 2 available-1 with a "mini-oxygenator" and 1 without. well....i put a 74 vintage 360 init with a new cat and claimed i was pulling over 10,000 combined GVW to get past our e-check crap.
i heard some of the boys say the inspection station have detailed printouts. But i agree with the previous post, plenty of new oil wrenches that gawk at my carb...seems the new crowd would have no idea what to do with all the adjustments....
ok here's a good question i also have an 87 d150 and i cant find the bolt pattern, offset, or rear spacing to buy aftermarket rims. it has a 318 which i doubt makes a difference but it is long wheel base which i know is different from the short wheel base. i currently have cragar 330 series rims..i think they look the same but the previous owner used spray paint on them which i spent days scraping and pressure washing off ( no shop so i couldnt take the tires off and sandblast) but the center was white and the only chrome part was after the spokes. anyways any help on this is greatly appreciated.