Dick,
We're going to have to agree to differ on this one!
Agreed that Dave Campbell was the usual bass player for the 'Travelling Rebels' (he did the UK tour in the spring of 1960, for example - see my article on p.24 of Pipeline magazine No.97), but Al Casey did some 'travelling' too.
Here's Al on stage with Jimmy Troxel in Sydney, Australia

- Al Casey on stage.JPG (21.44 KiB) Viewed 10463 times
(There are other pictures of Al on stage with The Rebels).
Apart from the fact that Niki Sullivan wore glasses, what other evidence is there?