This listing is for a New Aftermarket Mercury 70-125 HP 3/4-Cylinder Lower Unit, which will fit motors from 1987 and up. This unit will replace most 3/4-Cylinder 2-Stroke Lower Units from 1987 to the present and most 75-115 HP 2-Stroke Lower Units below Serial No. OT801000; this applies only to lower units with a 4.25" Bullet Diameter. This unit will not replace a 3-Jaw Lower Unit unless the shift shaft in the midsection is changed, and it also will not fit models with a plastic water pump housing.
The image below shows the OE case marking for 3-jaw (1997 or earlier) or 6-jaw (1998 or later) units. You will notice on the 6-jaw unit there is a 45° machined line just forward of the trim tab bolt hole. The 3-jaw case will NOT have the 45° line. All SEI units are 6-jaw, however they do not have the 45° machined line.
When replacing a 3-jaw gearcase with a 6-jaw gearcase, the shift shaft and linkage must be replaced. The Midsection Shift Shaft Kit ($149.99) has the shift shaft and link as well as all applicable bushings and nuts. Since the powerhead needs to be removed to replace the shift shaft in the midsection, this kit also includes a new powerhead base gasket. It is a universal kit that includes 2 powerhead gaskets, so please use only the appropriate one for your motor. This kit will work for 75 HP - 125 HP. Tiller models do not require any modification.
This unit comes with a three-year fault-free warranty. For further details, please see the complete warranty at https://obparts.com/sei-marine-parts-warranty-policy/.
When placing an order, please verify the following:
- Gear Ratio: Available in 2.07:1 and 2.33:1
- Engine Type: Two Stroke Carbureted, DFI [Direct Fuel Injection], or 4-Stroke
- Shaft Length: Available in L (20") or XL (25")
If you have any questions about whether this lower unit will work for your motor or gear ratio, please send us an email with your engine model and serial number to email@example.com.
All units are drop-shipped out of Florida with a flat shipping fee for orders placed in the Lower 48 of $15.00. Florida and Kentucky residents will be charged an additional 6% sales tax.