Help! Knocking noise when engine first comes under load
I need some help from fellow jeepers! I have a 2001 Wrangler TJ 4.0L manual 5 speed, when I accelerate from a stop and the engine first comes under load I am hearing a knocking noise, maybe 4 to 5 hits, that goes away as I accelerate, but I can feel a lot of shaking through the floor and the shifter. The sound seems to come from either the transmission or rear of the engine.
To try and fix this I have tried several things:
Replace transmission mount (stock one was cracked)
Inspected engine mounts, both are in good shape
Replace all u joints in front and rear driveshaft (5 total)
Recently changed all fluids:
Transmission, transfer case, engine oil
At this point I am out of ideas and engines aren't really my area of expertise. It's this some kind of drive line issue still, or something in the engine or transmission?
My jeep isn't a daily driver, so I haven't had to break down and take it to a mechanic yet. I like to fix things myself and I learn quickly so I thought I would ask around before taking it in. Thanks for any help you can offer!