My favourite is a chunk of 2x4 about 4 inches long with a groove cut in it. Or if the Jack is 3 ton rated lift the whole front or rear from the centre on the crossmember/Axle or in a pinch under the ball joint at the appropriate wheel. Please note: This is simply what I do myself when using Jacks and in no way constitutes any sort of professional advice or reccomendation. In other words don't try this at home kids!
I have a pinch weld adaptr for my jack as well. It is a bit different from that one though, as it is a 4" x 4" metal piece that is cast with a groove down the center. The entire thin is coated in rubber and it is great for supporting the motor and other stuff you don't want to do with a regular saddle.
Yeah I was looking for something soft like the rubber one you have Wes. I've been under the ser a few times and its already starting to bend that pinch weld.