According to my Weaver catalog collection (which ends in 1996) the 4-6-4 Hiawatha was offered in November 1995. The designation was QC1080L for the 3 rail, QC1080S for 2 rail and QC1080LP*** for the engine with MTH protosound. The engines were controlled with a QSI DCRU board.
***My error - that should have read QC1080LP - not, as I originally posted "LS" - that's the trouble with trying to look at the box labels and the price sheets all at once. Sorry for the confusion.
The cars were obviously offered later. The first versions did not have interiors.
The first ribbed 5 car set was G1230-L which contained an observation, express tap, parlor, coach, and diner. There were two add on cars G1615L and G1616L (for the two rail versions the suffix was "S").
G1615L was a named car - Chandler. I don't know the specifics concerning G1616L
The two rail version of the 5 car set was designated G1231-L
Below is the G1230-L set with a G1615L add on - the Chandler is the bottom car in the second picture.