I have 180000 miles on my trucks limited slip OE rear end, some towing and heavy loads. I noticed leaving the driveway this weekend (unloaded on dirt) it was acting a little choppy. I've never noticed this any other time but I dont drive it much unloaded. It's my wife daily driver, I drive a ranger due to my 100 average daily drive. It operates normally on pavement so...
I've had offroad race trucks with spools that nibbled and this is a little like that. I don't want to just change fluid if it is toast.
It is in need of service/oil change or replacement?

 

I would change the fluid and have a look inside. If there is a problem with it, I would think it would show up on paved roads also.

 

I assume all these newer oils that are Limit-slip approved are good.
Ive always checked and topped off with Lucas products.
The last time it was open was 100000 mi check up at the stealership (coupon deal) I usually leave well enough alone, if it ain't broken why fix?

 

Lucas products are good. Just make sure the fluid you use specifies 'Limited Slip' on the bottle. I did both of my axles with Valvoline SYNPower Fluid, 75/140 for the rear and 75/90 for the front or whatever the recommended fluid weights are, I might have forgotten.