I cannot believe it, but it has been nearly 30 years since I last assembled this Technical Lego 856 Bulldozer. The kit contains original box, instructions and all the parts to make this working model. Scans of the instructions for the 856 can be found at Peeron.com
I think this is one of the better Technical Lego sets - it has two sets of rack and pinion to control the bulldozer scoop - one for tipping the scoop, the other to raise and lower it. All in all a good lesson in rotary to linear movement via rack and pinion and then linear to rotary movement via push rods.