w900a sleeper ?

The A models were as tight or tighter than the 359's. You could roll the pass window down from drivers seat. There is a wall behind the seat. I had a 79A model with a late 80's aerodyne I wish a 100 times I woulda kept. Cab was small but once you made it between the seats you had a rompin room lol

 

I run a 78 W900A now, daycab. I'm not huge, but not small either. It's tight, but I enjoy the truck a lot. Just restoring it now actually.
Has a 22" steering wheel that is my personal measuring device to let me know I need to lose a few pounds when steering starts to drag a little...
Some folks take these trucks to Indiana Custom Trucks in Shipshewanna, In. and have the cab and sleeper hole cut open big and put a walk in boot frame between them so you can get in better, and put your seat back further. If you're going to run one full time, I'd suggest it myself. Mine's a rollback/flatbed, so I don't live in it.
My daily driver is a 2000 W9L with a small hole, 60" flat top that is the same way...wish I had more seat/leg room but it's basically the same cab almost as the A model give or take an inch or two. I run locally, in and out all day, so again no need for me to cut bigger holes in the back just for bragging rights.

 

The cabs are narrow and small but I feel more comfortable in them then I do in a big headed condo truck. I'll say the best thing I did though was cut out the rings and boot of a wrecked uni-built Pete and fit them into my a model