Love the Saundersbird! Very cool bass!
In reference to the bass, yes, it is mahogany, I was a bit taken back by that section being clear coated, definitely mahogany. It's actually a reasonable weight, I'd say not much over 9. With a strap it's balanced, leaning on neck heavy however that's just me being a stickler.
I don't currently own a bass amp, so I couldn't say one way or the other on actual tone, maybe I'll run it in the local music shop this weekend.
It resonates *very* fully, the bridge looks to be a milled Star(kahler) brass bridge and likely same brand brass nut, tuners show no markings so I'd assume you're correct on the fender style, probably whatever brass bass tuners they could get per my understanding of the early charvels, they didn't do a ton of basses that era.
The pickup is a replacement, who knows what the original was. I assume it's a quarter pounder or lightning rod, will check this weekend.
As per sitting down, yes, it's rather, well as noted, neck heavy, but with the curved bottom horn and giving it a little vertical angle, quite comfortable, but this is coming from a person who played the extreme metal guitars for many years.
And yes, that finish. I smiled inside when I saw it in the sun, it's not just nuclear yellow, it metallic nuclear yellow. I didn't look at it close enough to determine if it's metallic or pearl, but it certainly has a nice sheen to it in person. Doesn't hurt that early charvels seem to use this finish too.
The only flaw if you can call it one is that I can feel the skunk stripe through the finish a few inches worth closer to the headstock.
Weird, wild, very cool bass. Can't wait to take her apart and get some dates, but 81-82 is looking right per the information I can find. The stuff that pops up being models from 86-92 per some bluebook like site don't really mesh with the stories of people, I highly doubt there was ever a actual run durring that time, seems like only a handful were made around 82'