3 Speed Transmission Identification

[CA Victoria]

Information in VanPelt's V-8 Transmission publication shows two different 3 Speed top shifter cases.

I was under the impression that the transmission case with the long rib on the bottom of the case was a later production case. I pulled the transmission from my 50 pickup and noted that the transmission with the long rib had an 18-2,5xx,xxx serial number which puts it somewhere around 1936.

Based on this finding were both cases used interchangeably throughout production of the 3 speed top loader?

[Charlie ny]

Tim,
The # you are after is at the rear of the case beneath the support boss
that the rev idler and cluster shafts pass thru. It will be 78- something. These
#'s are cast in not stamped.
Charlie ny

[CA Victoria]

Added a couple of pictures. This case is the early 48-7006 case which is correct for the serial # lineage. Obviously there were cases made with the long rib before the 78 series. If I had not looked at either the casting or serial # I would have said it was a 78 series case........... I had not seen an early case with the long rib before......

[rotorwrench]

There are cases out there that will make you scratch your head. There was even a 99- case for the Mercury cars for that first year but we've only had one photo of one of those show up on the barn. The later cases have a deeper bottom so all the different combinations of input shaft & counter shaft clusters would fit in there. There were even some made by sources outside of FoMoCo that were probably contracted as spare parts after Ford stopped production on them.

[CA Victoria]

Makes for interesting conversation. I bought a trans case, turns out it has a 99A- serial # for a 1939.

[Bruce Lancaster]

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Basic families of top shift cases:
1932...several variants
1933-4 with tapered bellhousing area
1935-6, first inch of bellhousing is straight to accommodate larger clutch options
1937---about 1952 in pickups. Some variations in castings, after 1947 engine number was no longer stamped on bell.

[svm99]

I've seen both the "48" and "78" cases with the rib, I believe it was a mid 30's feature as the "78" cases which were introduced w/ the 29T cluster seem to not have the rib, at least in my experience. I do not know the reason for the rib.
Thanks Paul J.

[Barn Junk]

Originally Posted by Bruce Lancaster

Basic families of top shift cases:
1932...several variants
1933-4 with tapered bellhousing area
1935-6, first inch of bellhousing is straight to accommodate larger clutch options
1937---about 1952 in pickups. Some variations in castings, after 1947 engine number was no longer stamped on bell.

Good list. Would add:
1932-4 Through-out shaft bellhousing position is farther forward than later cases.

Most 1936 "48" cases (except early) have the bottom rear rib like the 1937- 1940 cases and appear to be physically the same.

Starting in 1941 pickups the bottom of the case was deepened for the 29T cluster and the bottom rear rib was eliminated.

[Bruce Lancaster]

The '32-4 positioning of the throwout is part of the same change as the cone-to-straight change in the bellhousing...they needed a bit more space right there as bigger clutches became available in '35