Hi Stan, I'm sittin up in the wee sma' oors as I fell asleep after dinner!
I've been using Summit and Speedway too as I've had good results dealing with them. I've got the advantage of having good friends in Virginia for sending me bits when I need them.
You could have a look at http://www.dannyschevyparts.co.uk/
He's a good guy even though he's a sassenach grin and has helped me out with quite a few things. If he hasn't got it in stock he can order parts in for you.You could also try http://www.truckandcarshop.com/ as well!
Or click on links in the Stovebolt page there are a number of suppliers there too.

I would help you out with the gearbox but mine came without engine and gearbox,sorry! Hence the 350/350 set up.
It was basically easier to source than a 'Stovebolt'
Good luck John (Jock)

1950 Chevy Advance Design 3100 in Scotland
In the Stovebolt Gallery
More pix on Flickr.
I've definately got this truck thing in my blood ... my DNA sequence has torque settings
"Of all the small nations of this earth,perhaps only the ancient Greeks surpass the Scots in their contribution to mankind" Winston Churchill.