GM Inside News Forum - View Single Post - 8.1L & 4L80E/4-L85E Transmission

mr_udy · 05-01-2008, 12:35 PM

Earliet Allsion 5spds did not have a selectable 4/5 (overdrive) gear. Newer ones do...nice to be able to control OD. GM does have a tech service bullitin to add a switch to the older units.

I've heard a couple guys say they like the daily driver performance of 8.1L with the 4L80E (2500 sub and Ava) over that of the Allison in the HDs. I try not to drive mine unless working it...cant afford too at 10mpg...

05-01-2008, 12:35 PM	#8 (permalink)
mr_udy 2.5L Iron Duke Join Date: Oct 2005 Posts: 20	Re: 8.1L & 4L80E/4-L85E Transmission Earliet Allsion 5spds did not have a selectable 4/5 (overdrive) gear. Newer ones do...nice to be able to control OD. GM does have a tech service bullitin to add a switch to the older units. I've heard a couple guys say they like the daily driver performance of 8.1L with the 4L80E (2500 sub and Ava) over that of the Allison in the HDs. I try not to drive mine unless working it...cant afford too at 10mpg...