Page 65 - OMC_Catalog_Flipbook

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UPPER GEAR SETS (1973-1985)

GLM is first in the marine industry to have all of the

OMC upper housing gear ratios.

Different size engines require different
gear ratios in the drive. The manufacturer
changes these ratios with different gear
sets. The gear ratio change is in the upper
gear housing*. All 1973-1985 OMC upper
gear housings are identical** except for
the tooth count on the gears. Below is
a chart showing the tooth count for the
different size engines used with OMC
sterndrives.

All GLM upper gear sets come with:
GLM No. OEM No. Item
21544 382212 Bearing
21545 379585 Bearing
21547 375761 Bearing

Engine Teeth on Original Gears GLM No. OEM No.

4-Cylinder, All 21T/18T 22518 982244

V6, 3.8L, 229 CID 21T/20T 22530 982835
L6, 165 HP 21T/19T 22514 984262
V6, 4.3L, 262 CID 21T/19T 22514 984262

V8 Ford, 5.0L, 302 CID 21T/17T 22512 982259
V8 Chevy, 5.0L, 305 CID 21T/17T 22512 982259

V8 Chevy, 5.7L, 350 CID 21T/16T 22510 982261
V8 Ford, 5.8L, 351 CID 21T/16T 22510 982261

*All lower gear housing ratios are either 2.0:1 for the four-cylinder engines or 1.83:1 for the six and eight-cylinder engines.
**The original driven gears in 1973 and 1974 upper gear housings are not machined for a centering cone. All 1975 and newer driven
gears and all GLM replacement driven gears are machined for a centering cone. A new drive shaft with shorter splines and a centering
cone must be installed when replacing the original (non-centering cone) driven gear.

Rebuild your OMC powered boat with high quality GLM parts!
GLM is the source for OMC parts!

www.glmmarine.com 65