First, thank you for allowing me to post a question here. If I have posted in the wrong section, would a moderator please move the thread to the correct section?

Please forgive this dumb question:

My father just died and left me a well-used 1988 K2500 with perhaps 200,000+ miles on it. It runs well and I've changed the oil (BADLY NEEDED). The transmission shifts fine, but it goes into gear just a tad rough and I think it needs a bit of transmission oil. I figure if the oil was that bad, the transmission lubricant may be down as well. Dad was ill with cancer for a while and could not maintain it, so it sat for a while with no running.

Here is the problem: I have never owned a truck before. I know little about manual trannies as well. Could someone here suggest the best lubricant to use for this gearbox and perhaps a thread or site which discusses how to add lube to the transmission?

I do all the work on my cars, mechanical and electrical.

Thanks in advance, Bill.

 

If I am correct you have a New Venture 4500 (NV4500) transmission in the truck. In the glove box look for RPO codes MT8, MY2 or MW3.

MT8 : TRANSMISSION, MAN 5 SPD, NEW PROCESS, 109MM, 6.34
MY2 : TRANSUISSION, MAN S SPD, HMD, 85MM, 4.D2 1T, O/D
MW3 : TRANSMISSION, MAN 5 SPD, NVG, 1109MM, 5.61 1 , O/D

Here is a link for information on the NV4500 which includes fluid specs.
New Venture Gear 4500 transmission - Wikipedia, the free encyclopedia

 

Thank you, Richard! It's a 5 speed, so I'm guessing you're correct.

Thanks for the help! Bill.