Where is the TCM located? Van has the 4.3L Vortec engine. Van shifts rough.

Hello, Dave here, contributing to RepairPal and providing expert advice since 2010. You mention having a scanner installed - what are the faults that have been set? Why are you looking for the TCM? Codes set are going to give you tips for troubleshooting. Going around the process of figuring out what is wrong and instead trying to act to do the most inexpensive thing to fix your vehicle - may be a desire but probably will not yield the results you're hoping for. I believe you likely have a internal electrical or mechanical transmission concern that will require more advanced troubleshooting to resolve. Reach out to a shop near you for help. https://repairpal.com/auto-repair-near-me Click the link or call us at 877-913-1554. We'll gladly find you a certified RepairPal shop in your area.