A500 42RH

Hi you all.
In the process on renovate an 42RH from a dakota 3,9 to put in my car. I have read a lot of threads about the car work needed to be done and finally started.
On the gearbox on the left side close to the split right over the colerfitting. Whats it for. Messure pressure.
Second i have a picture i saved of the right side with some fittings and seem to remember something about OD and Lockup.
Any input on how when and what.
Third. Can i use anything from a 904 Lockup in the 42RH. maybee the forward clutch and shell because it contains 5 instead of 4 clutch disc. I have 275 to 300hp.
Fourth. I reed somewhere abot drilling a hole bigger in the OD
have a good one.
Johan

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