Would you know anything about this?

Ertl makes some die cast farm equipment in a variety of scales up to 1/16.

http://www.ertltoys.com/brand/farm_const/2004/index.shtml

Don't know if they have what you want but its the only stuff I've seen.

Somebody makes some modern construction equipment but I don't remember who the manufacturer was.

Vintahe Aircraft,
Are you looking for kits or die cast?
The range of d.c is enormous and scales go up to 1/10 but the prices are not cheap.
If you are interested in d/c let me know and I will email some details to you direct.

Cheers, Pete.

In the early 70's Ertl produced a series of farm tractors , ploughs and dump wagons in 1/25th scale. A few years back they repoped the John Deere 4430 tractor and the JD 310 backhoe. These were available through John Deere dealers. They still show up at swap meets.
Unfortunatly the 1155 Massey Ferguson and the 1066 International tractors were never redone
Carl

I saw a few John Deere tractors at Wal-Mart the other day.Toys,but nice.