Yes you can. A lot of people don't change their trans fluid and filter because its so messy, then they forget about it, then after a few years, well, you know the drill.
So, if you'd pull your pan, put in a drain plug, new pan filter, and since you have a oil cooler, why not install a spin-on trans filter? I Love mine, because when I change my filter on my motor, I change the spin-on that goes to my trans also. When you want to change your fluid, use that drain plug! That spin on will catch shit that the bottom pan filter won't think about catching.
Just think, whens the last really technical auto trans. filter update been? WHEN? Oh, thay haven't changed much the past 40 years, have they? Does your motor have a torque converter? If so, do you have a trans temp gauge? On a good stout motor that has a slippery converter behind it, your putting alot of heat into that oil/fluid. The #1 cause of trans. failure is heat. Trans fluid breaks down, does not mix well with water, and doesn't have a long service life.
Spin on filters keep your trans clean, the extra surface area helps cool, and that drain pan plug allows you to drain the fluid before the stuff gets old and stail. A win-win situation.
But go ahead and take a bath in that trans fluid every other year, put alot of undue wear and tear on those trans pan bolts. ( I have studs in mine). I think that the chrome housing and the Tech-ness of it adds to the look of our little cars.
I know the blown big inch 6 cyl. makes my trans sighs relief everytime I change it ( that spin on filter), because I'm putting out some brutal torque, when that trans is cold, its getting hammered, bigtime.
Just a little something to talk about. Do you need it? Probably not. But I do. If you have a mild street setup, you can get by with changing your filter every few years. How often do you drive your T? How many miles?
Think of it like this, if there was a pan filter in the oilpan on your motor, does it not make sense to use the spin on filter to keep you oil clean? Why not do the same with your trans? That old trans. pan filter is old tech, I'm looking for the trans folks putting spin-ons before too long anyway.
The Newer Beetles the last 10 years or so, you know they don't have a dipstick on the trans? No way to add oil, is there? The shop has to right? Hum, makes you wonder. A lot of people don't know that the trans. even has filters. What I'm trying to say is since you have to drain your fluid every so often, why not make it easy on yourself, get a good spinon filter, to keep your fluid clean, then when you have to drain it, you got a plug in your pan.
What ever you want to do....