All right, here goes my bone head question of the decade. I threw away my invoice from Summit Racing when I bought my headers back in 1996. The boxes they came in are gone, etc. For the life of me, I don't recall if I bought the 1 3/4" or the 1 5/8" model. Is there a stamping on the headers anywhere that would tell me or should I measure the tubes with a measuring tape? <<(Probably answered my own question here)

measure. They made both

Yea, I can't remember if I told the guy I wanted the 1 3/4". Oh well a measuring I go. Either way, they have been great on my car compared to the old cast iron anchors I tossed out. GM should have installed headers in our cars from the get go especially during the low horsepower engine years.

Well measured the headers and they are the 1 3/4"