I've carried engines on an old tire, but prefer the sled.
Made it so the weight is on the pan rails and just enough room to slide wood (2x4 or 2 x6) under to help move it.
The roof line of the cargo area is the disadvantage of loading and unloading - unless you have fork lift.
(An SJ not a Grand Cherokee but you get the idea)
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View attachment 1715539558