asiandriver
740 got 19mm front 16mm rear "standard suspension package" (GL & GLE) or 21mm front & 19mm rear "sports suspension package" (GLT & Turbo).
The "anti-roll bar kit" 9134925 from the accessory catalogue comes with 21mm front & 19mm rear sway bars, I bought one back in early 2000's and had it fitted to my 740 GL.
According to the accessory catalogue, this kit's not required for 940 from 1993 onwards as they got the bigger sway bars already as standard on all models. In fact I seem to vaguely remember 940's from 1993 got 23mm front sway bars, if I can find the reference I'll definitely post it.
As far as I know no 740 / 940 Estates were factory fitted with rear sway bars, although the accessory catalogue did list this kit as suitable for Estates as well.
760 sedan Mk1 IRS (1988-1990) has no rear sway bar but 960 sedan Mk1 IRS (1991-1994) got 18mm rear sway bar. The whole subframe is slightly different so you can't just pull the sway bar off the 960 to fit the 760. If you're really determined you'll have to swap the whole subframe but keep the original rear axle to maintain the diff ratio. I've had this work done by the dealer on my 1990 Volvo 760 GLE that I had in Taiwan.