Are Replacement Keys Available for Master Lock Trailer Tongue Lock Mod. 377 ML377KA

Updated 02/20/2026 | Published 02/16/2026

Question:

I need a key for my Master Lock Trailer Tongue Lock Mod. 377 Serial No. D457113. Do you have one? Please respond.

asked by: Gary M

Expert Reply:

Hey Gary,

While replacement keys are available for your Master Lock Model 377, the only way to know what key number is available is off the key itself, it's not stamped anywhere on the lock. With that said you have two options, you can have a locksmith pick the lock and identify the correct replacement key, or you can cut off the old lock and replace it with another # ML377KA. If you go that route, write down the key number just incase you need a replacement in the future.

What kind of trailer do you have the lock on?

expert reply by: Samuel C

Gary M.

2/19/2026

I took the lock to a locksmith, but he wasn't able to come up with a key. The Serial Number is D457113. Does that help? Please respond.

Samuel C.

2/20/2026

@GaryM Unfortunately, no. Serial number does not corollate to a key code. If you do not have the code of the Key, the only option is cutting off/drilling out to remove and then replacing.