rear axle from 132/argenta would be much closer match since only diference to 131 is panhard rod mounting point as far as i know
Upper control arm mounts are also different, 131 mounts are straight, same as the bottom, 132 top mounts are angled towards the centre.
now that you mentioned it, yup, you're right. i havent even noticed. believe it or not, i never had to change any of rear suspension arms on my 132s or on 131. meanwhile, i can remove and install back on ladas' rear axle blindfolded
i'm toying with an idea for some time now, i think that combination of 132 and 131 rear suspension would be the winning formula. straight lower suspension arms, as on 131 and 132, angled upper suspension arms as on 132, panhard rod as on 131 and lada, anti roll bar as on argenta volumex and lada VFTS, rear discs as on 125 and 132 1800, limited slip diff from my ex steyr 132 1800 automatic...
i'll try this combo on my "mule" car, lada with a fiat's twincam. might be interesting