I just changed the oil pan on a late friend of mines 92 TA vert (it rusted out, weird) I noticed the oil pan had a notch on the driver side for like a oil level or temp sensor but the pan didn't have the anything other than the weird flat spot. Looks like a vortec truck pan.
So we pulled the pan and plain as day, PM rods in this 305 auto car. We got it buttoned back up and I checked the pad 2 see if it is the original motor. Yup, vin on block matches the car.
His car is 8, k ish away from the last bird built in 92.
I'm wondering when the PM rods started in these cars?
Will post pix later.

 

From our other conversation, I wonder if you were right to think that maybe it changed around the same time they changed the valve covers from Silver to Black on the TPI cars in the last few months of production.

It would make complete sense. The Corvette already went to the LT1 in 1992, and the 4th gens were coming out with the LT1 in a few months, the TPI & LT1 engines were assembled in Flint, MI IIRC, (about 5 miles from where I sit) and the only difference between the Corvette Engine and the regular TPI engine was the fact the Corvette engine was given the "white Glove" treatment. They probably were gearing up for the LT1, and as the stock ran out on TPI parts that were interchangeable with the LT1, they did not see a need to order a small batch of parts to cover what few TPI engines they would make.

In production, if they ran out of a screw, that they could get at a local hardware store to work until they got stock back in, they would go out and buy the screw, just to keep the line rolling even if it was not exactly right... It would not be a stretch to think they would not do similar things to keep the lines rolling...

John