Exhaust ID/OD question

Truck: 1986 F150 2wd 5.0 EFI

I’m building myself a custom exhaust, I’m fully capable of cutting and measuring myself.  But, I’d rather not be driving my truck around with a cut exhaust while I wait for parts.

I figured someone ought to know, what is either the ID or OD or both of the stock exhaust as seen circled in the picture above?  Specifically where the y-pipe enters the pre-cat

Thanks

I don't know for certain, but it's gotta be 2" or smaller, probably 1 7/8" or something like that. Can you slide under there with a Vernier caliper and measure the OD?

I just did some exhaust work on my 5.0 with 2.25" pipe, and I know the stock pipes are smaller than that....or at least they are in my memory lol. YMMV.

The Y-pipe I will be buying for my truck I was told its 2" at the manifold flange and 2 1/2" after the Y pipe merger.

I also recall Hedman headers telling me the collector on their 86-96 truck headers to be 2" as well.