manual transmission fluid amount
To check transmission fluid in a manual you need to crawl under the vehicle and take the little rubber plug off the transmission on the side and stick your finger in there, it you feel fluid you're good. if you cant feel any you better put some in.
Basically you put fluid in until it is up to the bottom of the fill hole. An older truck like yours is probably due to have the gear oil drained and replaced.
Search GMC Sierra 1500 Questions
GMC Sierra 1500 Experts
Related Models For Sale
Used Cars For Sale