1980-1997 Mercury 20" Lower Unit 35 40 45 50 60 70 HP DT C# 1643-9539 6 MO WTY

This specific lower unit is in good condition. We have professionally inspected this unit to guarantee it to be in good, working condition. The paint does have minor scuffs and scratches, but nothing that will affect the performance. The intake screens are in perfect shape and are not broken or cracked. Please note that this does not come with the trim tab, the propeller hardware or the propeller. Given our unprecedented 6 Month warranty on every lower unit, you will never find a better deal on an OEM lower unit. Please add oil before installation. Purchase with confidence!  

Driveshaft measures - 21-1 /4" from the top of the water pump to the end of the pin
Driveshaft spline count - 11
Prop shaft spline count - 13

General Information

• Freshwater condition
• Opened & Inspected
• Professionally Cleaned
• New Impeller
• Pressure checked to 12 PSI minimum
• Shafts checked for straightness

Criteria to validate your 6 Month warranty:

• Core must be of equal or greater value
• Cannot be locked up - driveshaft must spin
• Up to 30 days from the date of purchase to send in your core
• Covers mechanical aspects ONLY
• Warranty begins from date of purchase

You will receive two copies of the terms and conditions for the lower unit six month warranty. One copy MUST be signed and returned with your core. Without a returned signed copy, the six month warranty will not be valid. 

Upon receipt of your core, we will inspect the unit to determine if it meets the criteria to validate the 6 month warranty. We reserve the right to accept or reject any core at our discretion. If you have any questions or concerns, please do not hesitate to contact us and we would be happy to help!

Please note that we will not accept returns for this item if ordered incorrectly. Please be absolutely sure this is the correct one for your motor prior to purchasing.

Location: Southcentral Outboards, Altamont, Illinois

35 HP 1984-1989
40 (2 Cylinder) HP 1980-1983
45 (4 Cylinder) HP 1984-1989
50/60/70 HP 1980-1990
40 (4 Cylinder) HP 1989-1997

Please note that this lower unit will NOT fit the following below.
30/40 (2 Cylinder) 1991 & UP

We have provided this cross-reference with the resources we have available in regards to fitment. This most likely will not fit every model for the years and horsepowers we have listed. We urge you to make sure this is the exact item you need by matching the part number to what is required for your motor. If you need help doing so, please contact us prior to purchasing and we would be happy to help!