Sounds like you have a winner!
Wonder what happened with the original running gear?

So your question is what "options" were available to the Sandman from new?
Towbar
Driving Lights etc?

Bumperettes are factory standard and couldn't be optioned either way.
Single 7" headlight nose cone. Fluted Guards. Full Length Roof Lining.
You should have GM Rallye II GTS style rims and these would be date coded.
GTS Sports instrument dash. GTS Sports steering wheel.
Radio/Cassette.

I'm sure others will join in.