Brake Line Locks for E-Brake

Has anyone used a Brake in-line lock for an E-brake? Wanted to hear any pros and cons.

https://www.speedwaymotors.com/Speedway ... ,1970.html
Model in link above says not compatible with silicone Brake fluid (DOT 5)

Would a Stainless ball valve do the trick with DOT 5 fluid?

another sample valve:
https://www.aircraftspruce.com/catalog/ ... evalve.php

Granted, a little more effort adding a brake line in the cab to add brake lock for rear drums.

A line lock is not legal for a parking brake, here. I would think a line lock is not an approved parking brake anywhere.
Line lock systems can and do lose pressure. The only approved systems require a mechanical linkage, not hydraulic.

Line locks can be used for additional braking when winching or other use when someone is in the cab and can deal with pressure loss, the should not be used anytime someone is not in the cab, so no not acceptable for an E brake.
An E brake must be operable with a complete hyd failure to be legal.

Thanks for the correction guys.

It so happens PA does require a separate E-brake system in case of a failure in main braking system. The mechanics of drum brakes or drive line brakes is what seems to make most E-brakes a mechanical System. I thought 4 disc E-brakes were using hydraulic for e-braking...but I see they also use mechanics to press out piston against the disc during E-brake.

c) Parking brake system. A vehicle specified under this subchapter shall be equipped with a parking brake system. See 75 Pa.C.S. § 4502.

(1) A parking brake system shall be adequate to hold the vehicle on a surface free from ice or snow on a 20% grade with the vehicle in neutral.

(2) The parking brakes shall be separately actuated so that failure of any part of the service brake actuation system will not diminish the vehicle’s parking brake holding capability.

I saw some guys using them in the off-road jeep community and thought it might be an alternative...of course i did not researching the legality of it.

Years ago my old K-3 came with a Micro Lock system on the dash, it had a SBC 400 with a 350 turbo with borgwarner overdrive scabbed onto it, done by someone else.

I used it once on a hill, trans was in park, but overdrive didn't fully disengage,

it bled off and truck rolled down the hill missed pedestrians, missed a power pole and a street sign, bounced up a curb went down a hill and landed against a Van's front tire in a parking lot,

was in a tourist town, about 50 people watched it, cops didn't ticket me, but boy was my face red, never again