1991 Friendship - Looking for prebuy info

[PinPilot]

Howdy to all!

I've got my sights set on a 1991 Gulfstream Friendship with the 8.3 Cummings and Allison automatic. To set the stage here, seller is asking $6500, and it has 101k miles. Cosmetically its pretty clean inside and out, but the paint is fading.

I have a few questions:

1. 4 or 5 speed? The owner says its a five speed, but all I can find reference to being available in 1991 is a four speed transmission. Does anyone know for sure which it should have?

2. The 8.3 C Cummins is only 240hp. Would I be able to add an injector plate to increase the HP, or turn up the turbo a few pounds? (If I do this, I know I need to monitor exhaust temps.) Seems I read in '91 they didn't come with the Bosch fuel pump, which is required to do the injector plate upgrade?

3. This floorplan has the wetbar in the kitchen area. (At first I thought the kitchen had two sinks - LOL). It has an icemaker below. Any thoughts on this setup vs. just having cabinets in that location, as most seem to?

4. The front window is cracked. It appears the front window is in two sections? What should I budget to replace this? I would accept a used window if available.

5. The diesel genset has 7000 hours on it, which seems like A LOT to me. It cranks and trys to start but never does. Owner said it worked last year. He thinks it just needs a fuel filter, but I have my doubts. Comments? Suggestions?

6. Dash air not working - seems like it never does on these older coaches.

7. Has new tires with less than 60 miles ($2200 he claims).

I'm free to test drive it over to a nearby RV park so we can hook up shore power and test some systems. He doesn't have the right connection at his home.

Any and all feedback is appreciated! Thank you!!!