1995 trx 300

1995 300trx transmission issue
Having a little trouble with my tranny…or so I think it’s the tranny.. This only happens in second gear and it’s making a clunk/grinding kinda noise…it’s like it’s In between gears maybe…but funny thing is you take the weight off the rear diff and the noise isn’t present. It’s a 2wd bike…just replaced bevel gear and u-joint…all the bearings in rear diff. I’ve heard this noise twice before…but now it seems to be present all the time now in 2nd gear…it seems to slip a little at the same time as the grinding and clinking is going on…

PLEASE HELP!!!