Lifting the frame (or vehicle) can be done by anything that can safely handle the weight.
The important part is solidly supporting it once it is at the right height.
Block the wheels good on the end not lifted.
If both ends will be off the ground at once requires a lot of care if you are jacking each end separately. If you block 1 end then jack up the other, there is almost always lateral pressure exerted on the blocks. Things can fall over if you're not careful.
Cement blocks, good jack stands, I've often used log sections. When the frame is at the right height, measure it and go out to the wood pile and slice 2 pieces off a 12" log and you got great support. Hint; the taller the pieces, the bigger the diameter for better support.
