My 'new' 1970 Sierra Grande

[davepl]

I just bought this 1970 GMC Sierra Grande Custom Camper Longhorn, w/ 402, buckets and console, AC, and a number of other options. Got it locally from another forum member, so you might well have seen it before.

I'm sure I'll have a ton of questions, but I'll start with just a couple!

1) It has three fuel tanks (behind the seat, one filler at each side of bed). How do these work? Are they all interconnected, or where's the switch to go from one to the other? And what does the gauge show, just the main tank?

2) It has Amps-Oil-Temp gauges, but one of the little pods is empty. Is there ever a fourth small gauge, like a clock or something? Or if not, was it used on the C40/C50/C60 series for something?

3) My understanding is that the 2500 Longhorn has the one-ton frame. Other than springs, what's actually different between that and the standard half-ton?

Thanks!
Dave