4th gear whines pretty loud

I just put a new 360 in my 71 Demon and a used 4spd OD. Its running good but has a low whine in 2nd gear and a loud whine in 4th (loud enough to worry me and cause me not to go on the freeway). I didnt make any adjustments to it, just added 90 wt oil and installed it. In fact, I dont know how to adjust the shift rods... Can anybody tell me the best way? and could this be my problem or something else? Thanks for your help!