The 221/228 gearcases fit three different types of engines. They are as follows:

3.0 Liter – V6 – Two Stroke (13 spline drive shaft):
(SEI 221-A20, 221-A25 221-A30 228-A25 and 228-A30) 
Around 2006, these engines changed from using our SE216 units to our SE221’s. This changed occurred at serial number 1B504989. The SE221 units are what we have been calling the “Verado Style” gearcases. There are some available gearcases that we do not replace. They are the Torque Master, Torque Master 2 and the Sport Master. These units all have the “Fat Shaft” prop shaft with 19 splines. The SE221 has a 15-spline prop shaft. The SE221 is considered the “standard” gearcase and may be referred to as a Fleet master.

2.6 Liter – Inline 6 Cylinder – Four Stroke (20 spline drive shaft):
(SE 221-A20F, 221-A25F, 221-A30F, 221-B20F, 221-B25F 221-B30F 228-A25F 228-A30F 228-B25F 228-A25F AND 228-B30F)
These engines are the larger horsepower Verado models. The SE221 will work on these units from 200 horsepower to 300. The SE221 gearcase is the replacement for the 4.8 Torpedo units only. We do not offer a replacement for the 5.44 Torpedo. There are larger horsepower models of the Verado, but the SE221 is not to be used on them. These units came originally with Torque Master, Sport Master or the 5.44 Torpedo lower units. Around 2019, Mercury came out with a family of V6 and V8 engines. Unfortunately, they decided to call them Verado. They do not have the same gearcases as the SE221. They also look the same as the SE221 from the outside. Remember the SE221 fits only the inline engines, not the V6 and V8 engines.

1.7 Liter – Inline 4 Cylinder – Four Stroke (20 spline drive shaft):
(SE 221-C20F SE221-C25F and 228-C25F)
These engines are the small horsepower Verado models. They range from 135 horsepower to 200. They all have a supercharger. There are no optional gearcases for these engines other than standard or counter. No need to figure out if it came with a Torque Master. There are inline four cylinder, four strokes in this horsepower range that the SE221 will not work on. These engines do not say Verado on them and are not supercharged. Unfortunately, the lower units look exactly like the SE221 from the outside.
Does not include install kit or anode kit.