I ran into a problem trying to install a deeper, B&M transmission pan on my 1968 Olds 442 ragtop. When I dropped the old pan, I discovered that my TH400's filter was held in place by the spring clip shown to the left, below. The hole on the filter lines up about 1/4th inch or so in from the tip of the clip. On the right is the supposedly-longer bolt supplied by B&M so the filter will hang down lower into their deeper, extended-capacity pan. The hole my longer bolt came from also did not line up with the hole in the filter.

It turns out that the early TH400s used a different filter that tucks up along the left side of the housing. My transmission is a rebuilt unit and I would guess they adapted it to fit the later, cheaper filters at the time it was rebuilt. Partsamerica.com still sells the original, early-style filter, which is the Fram FT1013. It sells for just under $20 as of September 2004. The B&M deep pan comes with an extension that will also fit this filter. Below is a picture of the filter with the extension attached.

An option would be to drill and tap the valve body in the proper place for the later filter locating bolt. I may do that once these filters become harder to get.