I would use dimensional lumber. Once you have weight on 'em, let the car settle for a minute.

I replaced my Sears jack, worked well for years , with an aluminium HF unit. It has two pistons, one of which needed persuasion to release, has, so far so good, but won't buy one again.

I have two jack stands that came with the Sears unit and have purchased another pair. One set is taller than the other, oh well.

I use a chunk of 4x4 on the pad to both raise the lift and to be nice to the car.

__________________
83 SD

84 CD

No pics. Just imagine a ham sandwich:

Bottom piece of bread is the jackstand, the ham in the middle is the plywood, upper piece of bread is the cars jack point. Yummy

I like 3/4" ply wood. Ply wood takes the guess work out of what type of solid wood to use, grain, whether it's going to split on you or not.

__________________
85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Ok that helps. 3/4 is thick but perhaps necessary depending upon the profile of the jack stand. I was thinking thinner, but it also may split or something.

__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (116k)
1991 350SD (206k)
1991 300D (228k)
2008 ML320 CDI (199k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (267k)

Past Diesels:
1983 300D (228K), 1985 300D (233K), 1993 300D 2.5T (338k), 1993 300SD (291k)

I bought the Arcan Hybrid floor jack at Costco. The best jack I've used. Totally smooth to release, no sudden drop, and quick to raise, 3.5 pumps and it's at full rise. Well built, by far worth more than the $99 price.

__________________
1983 W123 300TD US spec Turbo engine, with Euro bumpers and manual climate control, and manual transmission.