I've seen places that advertise Gates "green stripe" but they may have dropped it but Continental still shows it.
 Continental Aftermarket - Passenger Car Aftermarket (continental-engineparts.com)
Goodyear also
untitled (goodyearrubberproducts.com)
Sites down under still list Gates.

I looked thru Gates online catalog and there are no HD vacuum hoses listed. I did see of a bus parts site air conditioner/ truck vacuum hose. Could it now be a superseded solution?

Double Mountain Manufacturing LLC
EddyLucast@hotmail.com 
203-228-1961

When I did Dennis's Ford I got the vacume hose from NAPA in 1 ft lengths, it also had the steel tubing from the firewall down to the hydrovac but hose for connections and I used the same hose for the seat breather


Driving the greenies nuts
http://www.killcarb.com/

Original was plain steel tube on the vacuum side and I have no idea on the vent as it was rubber hose to a breather under the seat. I was going to use stainless tube on the vacuum side but didn't have enough, so went with what  I had, which was aluminum tube. Vacuum hose for the joints. On the breather side on my other truck, it looks like thin wall steel tube which is the same as EMT but without the aluminized coating of EMT. Not sure on the hose, as it has been replaced. 
 Since I was re doing the whole set-up and I had a correct air-cleaner with the port to run the fresh air side to the air cleaner, I eliminated the breather under the seat, in favor of using the engine air cleaner.
 The original plain steel vacuum side tube had rotted away. I think plain steel was used as that was all they could get in 1942. I could paint the EMT and no one would be the wiser.
 None of this answers the legality of the fresh air side hose.
 Truck vaucum hose can be had, but you have to buy it in 50' rolls, and I don't have 25 trucks that need  it.!

Geoff, 
My 77 Ford Ln700 used the same hose for the whole system, it had fabric molded into the outer cover. Sorry not a good pic, but the open hose laying on the floor is the vent line. It went up through the floor to a plastic vent/filter cap bolted on the rear wall. 20 years ago when I put the truck together I used a/c hose for the main line coming from the engine. At the time nobody had anything else available. If you can't find anything in the law that tells you what to use then nobody else is going to either. It's just a vent. I'm sure the EMT isn't up to any DOT specs, so just improvise. Could use Gates 27212(5/8) or 27213(3/4) but good luck finding it.  



mark h

ive seen some that have hose that resembles household vaccum cleaner hose on the fresh air side of the 
booster

we all know what your doing there  should work fine for the fresh air side  [more than enough]
but do ya really care abought the legalities there
or if anyone would know the difference anyway     
[including the truck creeper cops]      lol 

I'm fine on the vac side, and have run EMT for the fresh air duct to the hydorvac, I have hose to connect just not SAE 106HV rated hose 
 DOT says it has to be 106VH on the vacuum side, but I don't know what the law is in the fresh air side?
 I have 106VH on the vacuum side.
 I know it will work, just not sure about the law.

Trucks need 106VH not VL (heavy duty vs. Light duty?)  And no that is not what I need. I have enough truck vacuum hose for the vac side, but was wondering about the fresh air side, if that also has to be 106 VH hose, I don't know how or where I would get some.

Is this the same? Try this for a search term

Gates 27232 Power Brake Vacuum 11/32 inch x 36 inch (85 PSI) Hose

O'REILLY. ROCK Auto,...

Ozone-resistant EPDM cover
Textile reinforcement
Meets SAE 1403 Type L and complies with DOT FMVSS 106VL
Temperature Range: -40 Deg. F to +257 Deg. F (-40 Deg. C to +125 Deg. C)

Double Mountain Manufacturing LLC
EddyLucast@hotmail.com 
203-228-1961