Mostly a TR part only
However
Junkyard find....
Circa 1982 J-Cars
Mounted on the firewall.
Now
Per fellow member aminga:
There was a TSB on 86 PS pump to clear up a whine. The replacement had left hand threads.
The TSB recommended using a reservoir and return line from a skyhawk for the same year. It happened to have a left hand thread reservoir.
The bigger return line fixed the problem, the LH cap was just a side effect.
The Recall also included a new hose (Return I think) that was larger than the original) which was the actual source of the whine.
I believe they used whatever hose and reservoir they already had and the recalled one came off of a J-body (skyhawk)
I Think it was TSB 87133 and later 87315.
And some other members:
Take a look at the way the hoses connect to the fluid reservoir.
I'll bet yours are one on top of the other. There is an updated reservoir that places the hoses side by side.
I forget the part number, do a search on steering reservoir and you should be able to find it pretty quick.
I got the updated reservoir from gmpartsdirect.com and the problem was gone
Document ID: 267583
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#87-3-15: PW.STEERING NOISE WHEN PARKING
NEW RESERVOIR AND HOSE P/N - (Apr 28, 1987)
MODELS AFFECTED: 1986 AND EARLY 1987 REGAL T-TYPE
There have been a number of complaints of a power steering "moan" or "groan" during parking on 1986 and early 1987 T-Type Regals.
The cause of this noise has been identified as the power steering reservoir return nozzle, size of reservoir, and inside dimension of feed hose.
A correction for the noise is to replace:
Reservoir, Part Number - 25531140; Feed Hose, Part Number - 25531141; Return Hose, Bulk Part Number - 7828506
Return hose must be fabricated using bulk hose 7828506.
Cut hose to 7.5 inch (190mm) length.
See Illustration for routing.
WARRANTY INFORMATION
Labor Operation Number: T5142 Labor Time: .6 Hours Trouble Code: 92
I sometimes get mixed up
But there is a reservoir with the ports side to side - which I believe is the newer, quieter version
And one where the ports are top and bottom. This I think was the older version
Left hand cap vs right hand cap confuses me even more!
But to summarize - you should get GM Reservoir, Part Number - 25531140 which has ports side-to-side and a LH cap