JD has two divisions Engines and Tractors. The Engines Division makes engines for use in JDs Tractors. The Engine Div.s variable manufacturing cost is $6,200 per unit; fixed manufacturing costs are $300 per unit. The Engine Div. is currently working at 80% capacity. If the Tractor Division buys the engines on the external market, the cost is $7,000.

Using the general transfer pricing rule, what is the minimum price at which the Engine Div. would sell units to the Tractor Div.