Taking out th400 and noticed filter is wrong or different?

[1972_Buford]

I know that title sounds weird but I haven't seen a filter quite like it. Instead of being on the bottom of the valve body it is on the side and has a pick up like in the oil pan. I know it is a th400 but never seen the filter that is on it. It is on a 1972 c20 with a 350 cu.

I am leaning to the issues I have been having are the torque converter and will be changing that out versus rebuilding the transmission. It shifter nice and hard just would kill the engine. Sounds more like a torque converter. I am going to replace all the gasket I can along with the modulator and torque converter while I have it out.

Any ideas on the weird gasket? Can I modify it to use the other type?

Thanks
-B