How to flush an Allison T1000 tranny

Truck: 2001 Silverado K2500HD, D-Max engine
Mileage: ~200K

I'd like to flush out the tranny fluid prior to heading out to Colorado this fall. I've previously drained the pan and added 2 gallons of Castrol Transynd about 90K miles ago (along with the spin-on filter change)- but since, I collided with a deer, which resulted in a new tranny cooler and some unknown synthetic tranny fluid being installed. I was considering doing a complete flush- which I've learned involves around 21 quarts.

The local Chevy dealership was quoting just under $500 to do a power flush, but they'd only put the OEM tranny fluid back in- I'd prefer to stick with the Castrol synthetic.

Is there a way of flushing out the existing fluid myself? Any specific issues to be concerned with? Any help would be appreciated. Thanks.

Allison does not recommend power flushing ...See the following thread thread for DIY flush instructions ...

http://www.thedieselpageforums.com/t...ad.php?t=25765

:)

As per Allison (the manufacturer), a power flush will cause irreversible damage to the tranny. Sad the dealer recommended it (not sure if I'm surprised or not).

A full flush is simple, and can be done in your driveway (or where ever) with simple service tools and suitable containers. It helps if you have someone to help with the engine run steps (so you can watch and direct the fluid coming out).

Here's a thread that covers it:

http://www.thedieselpageforums.com/t...ad.php?t=29507