Allison Transmission Division of General Motors has announced it will cease manufacturing hydraulic transmissions to exclusively produce electronically controlled products for medium-duty truck applications. Transmissions that Allison will phase out include the MT 643 and MT 653, as well as the AT 545. The phase-out completes Allison’s full transition to electronically controlled transmissions for Class 5 through 7 mid-range, on-highway products, a move that began with the company’s introduction of the World Transmission in 1991. Replacing the medium-duty hydraulic products will be electronically controlled transmissions, including the 1000/2000/24000 Series and the 3000 Series. Allison will accept final orders for the MT 643 and MT 653 through June 28, 2002. Orders for the AT 545 will be accepted through Jan. 31, 2003. Allison Transmission will continue to make available service parts and ReTran for its AT and MT products as long as commercial demand warrants it, company officials said.