8L90E Locking Transmission Dipstick and Fill Tube 22173

GM did not give the 8L90E or 8L45E a dipstick tube from the factory. To check fluid on these eight-speeds you get under the truck, pull the fill plug on the side of the case with the fluid in the specified temperature window, and watch for the trickle. This assembly replaces that factory plug with a stainless braided fill tube that routes up into the engine compartment and terminates in a locking cap and dipstick, so a level and condition check takes a minute instead of a lift.

The tube end threads into the case where the service plug came out. The bracket mounts in the engine bay, the knurled aluminum cap locks the stick down so it cannot walk out from vibration, and the stick itself carries a stamped level indicator. Fittings are billet aluminum, the tube is stainless steel braided line, and the cap and bracket are 6061-T6 aluminum with a black mil-spec anodized finish. Reference number on this style of kit is 22173.

Fitment covers 2015-2024 GM 1500 series trucks and SUVs running the 8L90E, and Colorado and Canyon trucks running the smaller 8L45E. Both units share the same service plug location, which is why one kit covers the pair.

Where it earns its keep is on a fluid service. After a pan drop and refill on an 8L90E you have to bring the fluid up to temperature and set the final level, and doing that through the factory plug means working under the vehicle with the engine running. With the tube installed you set level from the top, and you can pull the stick later to look at fluid color and smell before a converter shudder complaint turns into a teardown.