The Middlebridge rear axle is very similar in design to the SE6a/b although it does have a different ratio 3.54-1, The axles are generally long lasting with a little maintenance the odd oil change and checking that the axle breather hole is kept clear it vent off any moisture, (Picture of location in the mechanical section of site) These axles can be noisy in operation and still be reliable in use. Check the brackets welded to the axle tubes they can fil with debris and become a rust haven, (just keep the hole clear at the bottom of bracket).