Author Topic: Seeking NP203/205 Driven Gear - Solved  (Read 3211 times)

Offline rich weyand

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Seeking NP203/205 Driven Gear - Solved
« on: June 11, 2014, 11:06:56 AM »
Anybody got a spare GM #3866798 (NP203/205 speedometer driven gear, 18 teeth, stamped "H")?
« Last Edit: June 16, 2014, 03:27:56 PM by rich weyand »
Rich

"Working Girl": 1978 K-10 RCSB 350/TH350/NP203 +2/+3 Tuff Country lift

Offline rich weyand

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Re: Seeking NP203/205 Driven Gear
« Reply #1 on: June 16, 2014, 03:27:19 PM »
Well, it turns out the speedometer driven gear was OK after all.  What happened: an AC Delco 90*-drive 1:1.300 ratio adapter and an aftermarket 10% reduction ratio adapter fought with each other and locked up.  The speedometer driven gear, not to be denied, twisted the .104 square-drive key into a pretzel.

Oh, and the driven gear was 22-tooth, stamped "M".  WTH?  Had to have been replaced somewhere along the way, as the only one installed in 1978 was the 18-tooth stamped "H".

So, I replaced the two adapters with one AC Delco 90*-drive 1:1.200 adapter.  It needed a .152 tang to .104 square-drive speedometer cable key on the transfer case end, and a .152 tang to .104 female sleeve on the cable end.  There are some on ebay, but people are inordinately proud of them.  I finally found them both with one vendor at reasonable prices.

So if you are looking for speedometer drive keys, sleeves, speedometer cable ends, ratio adapters, 90*-drive adapters etc., I can heartily recommend Texas Industrial Electric: http://www.texasindustrialelectric.com/  No on-line ordering or prices, but they are great over the phone, the prices were less than anywhere else, looks like they have about a hundred different drive keys, sleeves, and cables ends, the parts were in stock, they shipped next day (which they were apologetic about: "Well, you missed today's mail, so they can't go out until tomorrow.  Just so you know."), and they sent the correct parts, Priority Mail, for $5.05 shipping charge.  I called them Thursday, parts in hand today.

Hard to beat that.
Rich

"Working Girl": 1978 K-10 RCSB 350/TH350/NP203 +2/+3 Tuff Country lift

Offline Dan75k20

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Re: Seeking NP203/205 Driven Gear - Solved
« Reply #2 on: June 16, 2014, 07:21:30 PM »
I wonder if  1978 was the only year they had the speedometer connection on the passenger side also

Offline rich weyand

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Re: Seeking NP203/205 Driven Gear - Solved
« Reply #3 on: June 16, 2014, 08:03:39 PM »
Don't know.  Parts book doesn't show it in the exploded diagrams.
Rich

"Working Girl": 1978 K-10 RCSB 350/TH350/NP203 +2/+3 Tuff Country lift