yea, return that.
It sucks.
I've tried using it, then realized my neighbor has a pretty decent real one.
So i've been borrowing it.
does a TON better than the crappy attachment.
you can get a decent one from Amazon, HF, northern, whatever for ~100-150$
Just make sure it will go high enough to get to your transmission.
If you have to use blocks, you lose all advantages of having one. http://www.amazon.com/Grizzly-H6236...08-3457204?ie=UTF8&s=hi&qid=1184529711&sr=8-1
The biggest advantage to the "transmission jacks" over the attachment I saw, was that all 4 wheels were casters so you could roll it in, then straight back, etc etc.
I've got that one. I bought it 10 years ago to do the manual transmission in my Nissan pick up, and I really never had any intentions of using it for anything else. Fast forward 10 years and I've used it to pull at least a dozen tranny's and\or t-cases, even a big Ford E40D. It kicks ass for gas tanks too. I always say that if I had any idea I would use it that much I would have bought a better one.
That said, it's just sort of okay. It can do the job, but if you have money in the budget for a better one I would get a better one. A buddy of mine in Raleigh did grenade his by operating it with the impact wrench instead of by hand.
I got the 299.99 one from HF. It goes lower than the others, easier to get stuff under the frame rails, or working on cars on ramps. They put it $100 off every few months (saw it recently, might be on now), and use a discount coupon (there's a valid 15% now), and it's a good deal.