Bad Ast hydro-boost line routing

[astroracer]

I have pulled everything together for the van's brake system. I have all of the fittings, a local source for the HP hose when I need it and have everything mocked up so I can get an idea on how and where to route lines.
Parts:
'86 1 ton dually PS pump
1997 Corvette steering rack
1995 Astro booster and reservoir
All of the HP fittings are 16mm x 1.5 & 18mm x 1.5 O-ring style fittings
I will be running a cooler
I have one question...
The pump has two low pressure lines exiting out the back as you can see in the pic.

I cannot find any documention as to where these two lines go. I figure one is the return from the strg gear/cooler and the other is from? The big one out the top is the feed line from the reservoir so what does that extra LP line do? Help?
Thanks
Mark

[HENDERSON]

If I remember correct they are both return lines.

[MuscleRodz]

one is box return the other is hydroboost return

[dipren443]

Already been said, but if you feel more comfortable with another response confirming, one is the HB return the other is the steering gear return.

[astroracer]

Thanks guys, The only issue I have with that is this pump is off a hydroboost vehicle with a reservoir.... This is what has me confused. If the HB and rack BOTH return to the pump, what keeps the reservoir topped off? I know the donor truck also had a PS fluid cooler but that would simply route to the rack (or gear) return. I guess I can call a dealer to check on a diagram.
I know the HB unit only bypasses Low Pressure fluid when the brakes are applied, otherwise the High Pressure fluid just runs on through to the rack. I don't see that being a consistant low pressure source to keep the reservoir topped off, where-as the rack return usually goes straight to the reservoir not the pump...
Mark

[astroracer]

Okay, how about this? What if the truck was equipped with a ram style steering booster. I don't know if it was but that is the only other scenario I can find where the pump would need that extra return pipe... The steering gear actually fed the booster and THAT would need to return to the pump. I think I can probably leave one of the returns plugged. Dump the hydroboost low pressure output into the other and let the low pressure from the rack keep the reservoir topped off.... I will probably hit up a dealer to verify but I think this is correct.
Mark

[jlcustomz]

I have factory hydroboost on my 83'el camino.Pump output runs to hydroboost, then to steering. Hydroboost has return line to pump, as does steering. Both returns on reservior are same. Currently I'm using my 99' ls1 pump with a tee in the return line, does the same thing.
The hydroboost basically uses what pressure it needs ,& returns the rest. Make sense?

googled you a routing diagram.
http://ls1tech.com/forums/conversion...onversion.html

[Randy67]

The reservoir is really just a remote fill for the PS pump, plus some extra fluid capacity. I wish one of the return lines did go to the reservoir for nothing more than better fluid circulation. But, my 79 Dually has been operating this way since new so evidently it isn't an issue.

[astroracer]

The '95 Astro reservoir has two lines. One small and one large. I know the large one is the pump feed line. The smaller (low pressure) line is why I was thinking one of the assist units ran back to the reservoir... I guess I am going to have to make a trip to the dealer to see if I can get this figured out. Thanks for all of the input guys, I'll keep you updated. If anyone finds a diagram that explains all of this please post it up.
Update: I found a diagram that incorporates a reservoir and has the cooler return routed to it. This is for a '95 astro as far as I can tell...

I will do some digging but this is do-able with my components.
Mark