This is our special made pulley bushing for the Model D and GP tractors. Sometimes a crankshaft journal is so worn it must be ground. When this is done, new undersize main bearings are required. The Pulley bushing also shares this same journal which has been ground. Since it cannot be determined what the crankshaft will be ground to and make a bushing for that size, we make a bushing to accommodate the worst case. Our bushing will have .030" of additional ID material. The customer presses this bushing into the Pulley. You then measure your shaft, add .003" per inch diameter (about .009"). This will be the new ID bore for your pulley bushing. Set the Pulley up in a lathe or mill and bore to the new ID. This saves a lot of time and money for the customer that would ordinarily have to begin from scratch making one bushing. Our bushing is easily machined 660 bronze. OD, length and bevel are identical to the original John Deere bushing.