allen head drain/fill plug clarification

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Mar 19, 2006
Fort Collins, CO
Is there any reason not to use the OEM 10mm allen head plugs on all gear oil holes? As in drain and fill front axle, transmission (H55F if it matters), transfercase, and rear axle? For a total of 8.

Some posts mention that the t-case is aluminum, and not to use them there. Any merit to that?

And can I use the same OEM crush washer in all 8 locations as well?

Trying to be real specific so later searchers come up with a definitive answer.

I use them everywhere I can. Love the damn things..
This is what your asking about ??

Diffs use 'O' rings ? not crush seals on the fillers i kinda remember.

This ?

I got 'em everywhere, too.
Me too. Have them in every gear case. I just use the aluminum seals sold for them through Specter.

OK so since Im not into building it up as of yet , But in the buying area for the build up .
Are these plugs all the same size and pitch ? 8 covers the diffs , tranny , and transfer ?
If so ill order a bunch , putting orders together for my next trip into the double wides.

Thanks for the replies. Reason I wasn't sure is that when I ordered a bunch recently, the guy thought there was a spot they couldn't be used, and only sent me 7 (6 for gear boxes, one for oil pan).

I haven't pulled my oil pan plug in a few weeks, but it seems like it's 14mm instead of 19mm anyway (my numbers might be wrong, but it seems like it's smaller than the other plugs--new style pan).

Last night, I tried the allen plugs in all gear oil locations, and they seemed to work fine, and tightened up nicely.

So I just need one more allen plug, and a handful of crush washers for next time. They're so much better than dealing with all my old rounded off beat up plugs.
Some posts mention that the t-case is aluminum, and not to use them there. Any merit to that?

Toyota puts them in at the factory in aluminum cases in modern trucks (taco, FJC, 4skinner).
Yes 8 plugs, 2 each diff and two each in the t-case and tranny. They fit both the drain and fill holes

The one place I did have a minor problem was the tranny fill hole, the threads in the tranny were too shallow so I just ground off some of the plug and now it seats all the way.

The oil pan is a smaller plug so they won't fit there. When I made a new oil pan for my 3B I tapped the drain for the large allen plug thats in all my other gearboxes.

Ordered more today at the dealer. 2.34 each. Part number 90341-18021 for search reference.

Also got 2 different styles of gasket. I can't remember which is the folded steel (which I like better) and which one is the solid aluminum. So got some of each.

Gasket part numbers: 90430-18008 and 12157-10010. When I get them I'll post up which is steel and which is aluminum.

Thanks for the input on my question.
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90430-18008 aluminum O ring

12157-10010 folded steel crush gasket
Those things rock! How often do you get to install and upgrade using OEM parts for so cheap that is so superior to the original?
The aluminum gaskets are for use on the transfer case plugs only. The t-case is aluminum and using the aluminum gaskets will lessen the galvanic corrosion under the plug head.

Use the steel crush washers gaskets under all the plugs in the transmission and axles.

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