Dumb question- which TH350 trans filter?

[77 K20]

I have been a fan of WIX filters since it seems often AC Delco quality has went downhill. So in my search for a WIX filter I have found two different part numbers. 58878 and 58894

58878: GM TH350 69-85

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58894: GM TH350 75-83

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So will either work? Is one better than the other? I've changed filters before and never came across these different "shapes". And I've had some 700R4 transmissions in there also to confuse my memory even further.

 

[74 Shortbed]

This is all I ever used...

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[77 K20]

Finally found some info about the two filters. Someone on the gbodyforum posted a picture of a page of a TH350 book about filters:

"There are 4 types of filters. The first 2 are more like strainers than filters. Square in shape, they have a wire screen or nylon mesh on the top side. The third and fourth types are more rounded with one corner cut off and uses a Dacron filtering medium on their bottom sides. The Dacron filter for the 350C and the 250C have a bulge to clear the TCC solenoid. It can be used on non-TCC transmissions as well.
The major difference between a strainer and filter is filtering quality and flow restriction. The Dacron filter is much more effective. it will filter out particles as small as 30 microns. However because it is so effective it needs must be changed more frequently than the strainer-type filter. Otherwise it may clog, starving the transmission of ATF.
The metal screen and nylon-mesh strainers flow a bit better but allow more damaging grit to pass. So which type of filter/strainer you use depends on how you plan to use or service the transmission."

So...
Wonder how much more often I'd have to change the Dacron filter?

 

[HotRodPC]

I'd agree with this. I use the Dacron when I can get it. Like, the screen is good enough so if I need one that day and that's what I can get locally, that's what I'll get. If I'm in no hurry and I'm ordering a kit, then I order the Dacron. Change is every 50,000-75,000 miles you'll never have a problem with it clogging unless you have an ailing transmission. In that event, probably not a bad idea to drop the pan anyway, so change it while you're there if you've solved the problem.