What Trailer Coupler Lock will Work with My Bulldog-style Bolt-On Coupler for 5,000 Pounds?

Question

Question:

i am looking for a coupler lock that will work with this style coupler. i think this one will probably work ok, but i am wondering if there is a better one.

asked by: Rodger R

0

Picture of Trailer Coupler
(click to enlarge)

Expert Reply:

Hello Rodger,

There are a couple of different options for you. The one that you found, the Master Lock 1-7/8", 2", and 2-5/16" Trailer Coupler Lock - Gray - Keyed Alike # ML377KA, would work great. We have a similar style that also works: the Master Lock Trailer Coupler Lock - 1-7/8", 2", and 2-5/16" Ball Couplers # ML389DAT.

The kit that I use on my boat trailer when I am down at the lake is the TowSmart Trailer Coupler Lock Kit - 1-7/8", 2", and 2-5/16" Couplers w/ Hitch Lock & Coupler Lock # TS84FR. I really like this one because it uses the ball inside, and I clamp it down pretty tight. I have not had anyone take off with it yet!

I would say that the one you were looking at, the # ML377KA, would be the most difficult to try to remove.

What kind of trailer are you using this on?

expert reply by: Kate F

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TowSmart Coupler Lock Kit
(click to enlarge)

Kate F.

11/13/2025

Hey Rodger, how did the Master Lock coupler lock end up working with your trailer? Your feedback could help others choose between that one and the TowSmart or the other Master Lock option. Sharing what you found might guide others looking for a secure fit.

Rodger R.

11/13/2025

@KateF The coupler lock works, but it is very loose. I think it will at least slow a thief down. The hitch pin lock for the truck receiver works just fine. The other two locks, to lock the hitch from being opened doesn't work at all. The range of fit on those locks is very tight and they won't work on either of my trailers. Thank you Rodger

Kate F.

11/14/2025

@RodgerR I am very sorry to hear that Rodger. I see that you did go with the # ML377KA, I am surprised to hear it is a lose fit. But you are right, it will definitely slow them down, usually makes them move onto something else that is not locked up. If people could just be decent humans, we wouldn't have to worry so much about keeping our stuff protected. I really do appreciate you taking the time to share your feedback =)

Answer 1

I do have a solution for you, but the Master Lock Trailer Coupler Lock - 1-7/8", 2" and 2-5/16" Ball Couplers #ML389DAT that you referenced does not have the option to order the locks so that they are keyed alike. For a coupler lock…

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Answer 2

I really wish we could rekey these because we get the request all the time but we just can't do it. I have reached out to Master Lock on this subject before and they have told me you can take the Master Lock Trailer Coupler Lock item #ML389DAT to…

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Answer 3

Hello Robert, It sounds like you may be experiencing a bit of white-knuckle towing, which is never enjoyable. When a trailer doesn’t want to track straight, it can make every mile feel longer than it should. I do recommend a weight distribution…

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Answer 4

Hey Russell, that's a really good and tricky question actually. So, you definitely want to stay within the weight rating of the weight distribution hitch for the best and safest experience. It's not ideal to go over or under. The fresh water…

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Answer 5

Unfortunately it doesn't look like we've got any hubs that will work for this size spindle. For that reason, your best bet is likely going to be to replace the entire axle with a new one #20545I-EZ-72-15 which comes with hubs included with a…

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Answer 6

Hello John, thanks for reaching out. We do carry some 2" long 1/2" wheel studs, but I am sorry to say we do not have anything with a 0.56" spline diameter. What we have has either a 0.54" spline like part #DE52GR, or a 0.61"…

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Answer 7

Hey, Robert! There isn't a way for us to rekey the Master Lock Trailer Coupler Latch Lock part #ML94VR to an existing Master Lock key that you are already using. The good thing is that Master Lock uses a widely available key style that would be…

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Answer 8

Hey Chris, congrats on the new trailer! I've got two trailer dolly options that are going to work great with your 8,800 lbs 2026 Airstream Classic 28. One is a manual and the other is electric. Manual - Trailer Valet XL Trailer Dolly with Chain…

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Answer 9

Hey Tom! Great question. The Parkit360 Force Electric Trailer Dolly #PA96VR (5,000 lbs) and #PA46VR (10,000 lbs) will work on an incline. However, if the grade is more than 6% you cannot use the dolly. As long as your driveway is no more than a 6%…

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Answer 10

Hello Dave, thanks for reaching out. The reason for this is certain Jayco models use underslung couplers. The Parkit360 Force Electric Trailer Dolly #PA46VR is only compatible with overslung couplers. Overslung is a lot more common than underslung.…

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What Trailer Coupler Lock will Work with My Bulldog-style Bolt-On Coupler for 5,000 Pounds?

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