Our new heavy-duty differential coupler retains the same physical dimensions as our standard EB410 and ET410 coupler (TKR6597) but has less material removed for improved durability and impact resistance.  This new coupler is recommended if you are running in harsh conditions where your vehicle could see repeated heavy impacts.  For all of the ET410 owners out there looking to run larger 1/10th monster truck tires, these are a must!  The HD diff couplers are also ideal for carpet racing with frequent on-power jump landings.  They are made from the same material and are a direct replacement for TKR6597.