Originally Posted by Titanium
i will post the numbers and the diameter of the seal within the next couple hours. its for sure a 400 judging from the pan shape and length of the case.
Check the Spline count on the Output Shaft. Is it 32-spline or 27-spline?
TH400 has 32-spline count, TH375 has smaller TH350 size 27-spline count and a TH400 pan shape, the bushing is smaller on the TH375. It will have a 9-1/2" tailhousing also.
"" A medium duty version of the TH-400. On the underside of the trans, right where the tail housing bolts up, the letters "TH-375" can usually be found cast into the trans housing.""