Yah, that is interesting. I went and measured a 4l60 I have not installed and it was about 31 3/4 long, then I made a measurement on a 3speed I have installed and it was about 29.
Not sure how he got lucky, looks like he's using the stock truck pan too.
I'm sure he'd talk to you if you called him:
https://www.swaptimeusa.com/store/c2..._Products.html