amberbrush,
your post about the different Y-pipes ... very familiar.
I have an '88 ... y-pipe has the oval inlet to the 27" long"dual cat" pipe section.
I also have a '87 motor and exhaust system ... has the y-pipe with two round outlets which feed into a "cat pipe section" with same two holes.
I actually made an "straight thru pipe section to eliminate the cat on the '88. The oval inlet was a real task to reproduce ..plus the flanges at each end are NOT square to the pipe section ... nothings easy.
I made the "cat eliminator" 'cause I thought my cat was clogged ...found out not so.
Anyhow, until I finish my motor rebuild I won't know what Y-pipe I'll be needing, though I hope I can use the '88 y-pipe & exhaust on the '87 motor ex. manifolds.
dave