Rough shifting in lower gears

[tvdan1043]

My TJ 6-speed NSG370 transmission is kind of noisy when shifting in lower gears, and shifts rough from 1st to 2nd to 3rd. Beyond 3rd there is no roughness. This only happens when in motion. Parked I can shift through all the gears w/o any noise or roughness. A few "car guys" at work have told me I need to replace the transmission fluid but they can't seem to tell me how to do it on anything other than a Civic, and I can't find any how-to info on the web for the manual trans. I've looked at the diagrams in the owner's manual but I can't seem to locate anything that looks even remotely like the drawing. Can someone point me in the right direction?

 

[SteelHeadz]

STANDARD PROCEDURE - DRAIN AND FILL

1. With vehicle in neutral, position vehicle on hoist.
2. Remove drain plug (1)(DRAIN PLUG) and drain fluid.
3. Install drain plug and remove fill plug (1)(FILL PLUG).
4. Fill transmission with 1.5L (3.17 pts.) of Mopar® Manual Transmission Lubricant MS-9224 or to the bottom of the fill plug (1) hole.

The Pic on the left is the Drain plug, Pic on the right is the Fill Plug.

 

[Crazy4diesels]

One other note... These plugs are BIG metric hex keys. One, I think is 10mm the other is bigger, like 12-14mm somewhere. Why they're not the same I have no idea... The oil is special - see what SteelHeadz posted above for the spec. Best of luck - John