So here I am removing the fill plug cap on this Cat 54 winch and found it with a buggered up mess on top of the CAT fitting.
I suspect someone lost the original cap on the cat fitting and cross threaded another fitting on it followed by another cross threaded fitting on top of that fitting.
What a mess.
I went down the local hardware store this morning and this fitting is neither 1-1/2 or 1-3/4. I wet to the hydraulic shop and ran into another stump.
Cat proprietary threads? As this is nothing more than the fill cap, my desire is to either replace that which is there or not desiring to spend a bunch of money on a fill cap, cut this mess in 1/2 above the hex that screws into the top of the winch and then weld another steel fitting on that. That final steel fitting welded would be a bit more common a thread pattern to avoid this in the future by the next owner. Not wanting to lose another day with good weather, I am headed out to fix what I can in order to get things moving around here. The fitting will be waiting for a part number and if the price is too high, a fabrication in the future.
Sorry 'bout your bad luck Cat.
Thank you in advance! Your assistance is greatly appreciated.

Winch Serial number 19E220
Sales Model 54 AROANG (?) NO 6P979

It's a little hard to make out the parts diagram but it looks like that's more than just a fill plug. Seems there is also a filter vent involved.

How about a screen to filter out accidental large chunks? The vent might work to keep reduce condensation. The oil that drained was a milky mess.
If I can't locate a P/N, I will then cut the fitting in 1/2 and get a 1-1/2, 1-3/4 pipe fitting welded on it.
As for a vent, I might drill small holes (4- 1/32" at an upward 45 degree angle) in the cap and call it a vent.
I did get the cable retainer plate figured out. I wound up shaving it down to fit inside the cavity to retain the cable ferule. I also had to recess the head of the bolt a tad bit to get it out of the way of the cable on the drum. It's about done once I get the fill cap fitting dialed in.

Here's the parts info on the fill/filter/vent area for that winch.

Thank you for the illustration, I will give CAT a call on Monday and get the bad news.

"brucew" wrote:

Thank you for the illustration, I will give CAT a call on Monday and get the bad news.

The 6K6977 Cap, $42.48 and the two gaskets are available but not sure on the Adapter 8P2330 [plug], have to call on that.

I did a P/N search on Adapter 8P2330 and came up with about $107 on the fitting and another $20 for shipping.
It adds up to a bit more than cutting the Adapter 8P2330 in 1/2 above the hex and welding on a pipe fitting.
I will investigate the vent application at the local Cat dealer should he have the parts in stock for a look.