[Kurt S]

M40/TH400 Camaro totals
67 $226 1,453
68 $237 5,466
69 price was $222 for the L34/5, $290 for the L78.

The 68 solid lifter version was the precursor to the regular production 69 solid lifter version.
But doubtful the 69 pacers would use a 6 month old 68 trans when it was already available and in production at that point. And they didn't plan that far ahead on the drivetrains for a pacecar that didn't exist yet.