you can order the metal upgrade kits for them and all you get is metal tracks and metal drive wheel.
Metal Tiger I late tracks with ice cleats, guy also has black and silver non cleated. 99.00
http://matomart.com/prodview.php?p=729
Tank track Metal upgrade for 1/16 Scale M26 Pershing tank Black 69.60
http://matomart.com/prodview.php?p=703
http://matomart.com/product.php?c=1000007 <--- goes to the screen where you can pick upgrades for all the tanks. when you click on a tank the next screen is vendor brand option, click the blue and yellow Mato Toys one. there you will see gearboxes, tracks, etc.
I have bought like 5 tanks & numerous parts from this guy. A++