Another question is will the 4l85e bolt up to your small blocks? The 6.0 bolts up to both the 4l60e/65e and the 4l80e. But as far as I know the 8.1l comes only with the allison or the 4l85e. It could have a different bellhousing and not match up, I've yet to crawl underneath a suburban and take some measurements.

 

Jay Leno has the 4L85E behind the 572 in his buick that was featured recently in HOT ROD.

 

yea it doesn't say much about it except its a GM Performance Parts 4l85-e, which is basically a computer controlled, overdrive version of the TH400. he bolted it up to a 572ci big block