Jon: The fact that my uncle asked me a similar question about his RV tranny filter recently, coupled with the fact that I was bored this morning, I thought your question might make for a nice half-hour research project...
I suspect you're primarily concerned about filter MEDIA compatibility, among other things..? If so, I don't have a definitive answer, but here's some helpful anecdotal info:
The Filter Manufacturers' Council tech sheet "Filtration Media" (link at the Baldwin Filters website) addresses your thoughts with a comment, "...media designed for oil fitration cannot be effectively used for air filtration, and air filtration media cannot be used for coolant filtration, etc." Motor oils and ATFs are much more similar than dissimilar in the composition (at least when compared to other liquids such as coolant, gasoline, etc.), and as far as ATF's "thickness," the link below describes DexronIII/Mercon as an SAE 10w-20 oil (ATFs are not normally designated an SAE weight):
http://www.westpenn.com/sheets/atf.html
The MSDS link below confirms that ATF starts with your basic "Lubricating Base Oil - Severely Refined Petroleum Distillate." Sounds very similar to...you guessed it, motor oil. (Link deleted -- too long.)
Based on this anecdotal info, I personally wouldn't see any problem with using a "motor oil" media with a tranny. But there's other issues such as total media area (easy enough to address this -- how big does an actual "tranny filter" compare to a particular "motor oil" filter?), and bypass valve presence and setting.
This tranny filter is "6 micron," suggesting that finer filtration (PureOne, AC Ultraguard, Baldwin, Mobil 1, etc.) is best:
http://www.oilguard.com/Merchant4/m...tm&Product_Code=LFS+22825&Category_Code=other
The Baldwin #B-2 filter, compatible with the PH8A, is described as an 8 psi bypass "Microlite Full-Flow Lube Spin-on (also used as Hydraulic or Transmission)."
http://catalog.baldwinfilter.com
TransDapt #1156 doesn't seem to exist in the common filter cross-reference sites. If you can view one, take note of the filter base and presence of a bypass valve. You can then determine that "It's a Purolator (or Champion, Fram, etc.) base plate," another helpful hint.
At this point my SUSPICION is that you'd do just fine buying any PH8A compatible filter with a low bypass setting of around 8 psi to be safe (settings usually vary from 8-22 psi), preferably a large total media area version of one of the premium, fine-filtering brands mentioned above. An educated guess, but a good one, I think.
[ March 06, 2004, 05:10 PM: Message edited by: TC ]