I didn't have any trouble with my body lift, my interference came from my motor mount lift, I had to hold it in second and fourth. Then when I did my tummy tuck I had similar issue in first and third. Easy fix in my case, between the MML and TT, just removed the boot. After the TT I just put a few 1/4" diam washers under the front console mount and with the boot back on it's smooth as buttah now.
The transmission popping out of gear is more commonly caused by a body lift or t-case drop. Both of those increase the distance between the transmission and where the shifter exits the console which can restrict its throw enough to it can't shift the transmission fully into all of the gears. They increase that distance more than a motor mount lift does.
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