Is there a difference? My 97 had a flat flange going to a male donut on the passenger side the the drivers side had a male/female donut where the pipe meets the header. My buddy has one for a 96-98 and was thinking it would bolt on to mine no problem but some sites have different part numbers for them...

 

The 96 97 and 98 should all have the same mid pipes. The 94 and 95 models have the 5.0L engine in them so I think theirs would be a little different.

 

Shouldn't 96-98's have the same midpipe as the 99-04?

 

I have two attachments that show the 98 and 99 mustang gt o/r x's. If you look closely the only difference I see are the upstream 02 sensor bungs are slightly lower on the 98 than the 99, which may or may not cause concern. The other thing is that on the 99 slightly gets wider as it goes towards the motor so there is less of a curl for the upward angled pipes to make before the header like on the 98. Any suggestions? I feel like the pipe would still work if the 02 sensors reached cause the transmissions are the same and i don't recall anything else being in the way... to make the widened newer pipe eve seem necassary.