GM Step Van Vin’s Early 70-71

[HalfTonMarty]

I have a GM Step Van. No badges no grill. I do have a title, but, I can’t match up the first part of my vin to any of the charts I can find on the web.
It’s a steel GM step van either Chevy or GMC...

PS150J1XXXXX

P= Forward Control
S= I6
150? (Part I can’t match up) Normally on a P10 van it’s 105

J= Janesville Plant
I= Year.....71.

This title and plate on van match...
Any help would be appreciated....I have searched the internet extensively before asking for help......Thanks Marty