The spring compressor for the rear springs in the 124 chassis, as well as the 201 and 129 has an overall shorter fully extended barrel length. A regular KLANN knock-off compressor is too long and requires that either the outer or inner LCA end be disconnected to install the spring. To do so you get the spring compressed partly and then get it in position, then you use a jack to lift the LCA end up into position, the spring compresses the remainder as you do that. The compressor's Acme screw extends too far out of the spring compressor when it is used as it normally would be but there is no opening or space above the rear spring's upper perch for the extended screw so the LCA disconnect is unavoidable even with an internal type spring compressor.

If you get the vehicle elevated and positioned securely on all four corners you can usually position a jack under the LCA outer or inner end and carefully disconnect and lower it releasing the spring. You just need to be mindful of the direction of the force that the sprung LCA will impose on the jack and the way the jack's geometry will have it actually move when it's operated. Because the LCA end will move in an arc the jack head needs to move in a similar swing and not "swept" out from under it.

If you do a search there are more than a couple threads where this is discussed and people have described how they accomplished it.

If you decide to lower the entire subframe read the description particularly with regard to the subframe mount bolts and the cautions about getting them lined up and correctly started in their threads, it's not difficult to cross thread them and if you do you're going to have a bad day getting that straightened out. If you go the subframe route you need to disconnect the sway bar ends and the shocks to allow the subframe to drop very much, I'm not even sure you can get one side to drop far enough to remove the spring on that one side, maybe people have said they have but I haven't seen it myself. You've got the ABS differential sensor wire and the fuel filler drain hose on the passenger side to be aware of making sure they have enough slack as the subframe is lowered, also.