Have never been in a tank, but when at Arty NCO school at Ft. Sill, we did do a lot of training with the self-propelled howitzers. At the time we had 105mm, 155mm, 175mm (long tom) and the 8" SPs.
We got to drive them all around a course, fire them all, and use a recovery track vehicle to drag a tank chassis out of a mud bog. (had never been so dirty in my life).
Also, they broke us up into small teams and we drove an SP into the shop in the morning, had to remove the engine, set it on the floor, and reinstall it and drive it out before we could go home. But these engines had been in and out so many times, it was really quite easy.
If I remember right, the engine was a 8V71T, 8 cylinder, V configuration, 71 cubic inches per cylinder, turbocharged. Funny how some of the most obscure things can be remembered.
Luckily in those days I was a tall skinny kid that didn't have any trouble getting into the driver seat, no so sure I could do that now.
Vern.