Someday people will learn, Tamiya never made the Big Bear.
Marui, a company in great competition with Tamiya in the early RC days is the manufacturer of that truck. You have a Marui Big Bear. Here's a link to a restored one:
http://www.tamiyaclub.com/showroom_m...id=36066&id=16
Sadly the Big Bear is not a huge collectable, its rare, but the Tamiya name tends to bring in many more $$'s than Marui.
3300 with 8.4V would easily have caused the problem. Those old mechanical speed controls are not very durable, and over jucing them with a new high powered 7 cell pack is dangerous at best.