So now that the FISH is out of the bag... :)

[ViperMan]

Yes there are many 74 specific changes.
Small in the scheme of things but many.
The shoulder belts yes are 74 only. As is the connected ratcheting mechanism. And where they come out of the rear seat side panel. The seatbelts are fairly rare because of only the 1/2 year production when Mopar killed it.

The 2 knobs in center of dash are fresh air levers. Tje non air cars get fresh air openings on both sides. Air conditioning cars did not get the drivers side opening.
Let me know if there is anything I can help with. Challenger but is a 74.
I also concur with above noted hydroboost conversion. That is route I went.
Definately check alternator output at idle. If you have the lopy idle it can vary output enough at idle to increase and decrease light output. Suggest also changing them to be run with relays instead of thru on off switch as that is also susceptible to issues.

Details details details...
Mike.

Thanks Mike!  Is there a popular kit for the hydroboost that people often go with?

[Chryco Psycho]

I believe there is a kit for hydroboost  but it is far cheaper to just source the parts & make your own hoses .
Rock Auto has a hydro boost from a 90s chev truck for $130

[ViperMan]

So I finally had time to get the Cuda out of the garage and straighten her out.  I got the open vacuum port plugged, then had to bump the idle a hair to compensate (I think they literally dialed in the carb with a vacuum leak...   )  I got the kickdown linkage put together correctly and its running fine.  The car idles real nicely now and I took Ash around town for a little cruise today!  It was so nice!  Definitely need power brakes though - it's harder to stop than the Coronet was!

[Chryco Psycho]

Congrats on fixing the minor issues & getting out for a drive 

[Spikedog08]

That's awesome!  Glad you got to finally ride in the new car! 

[MEK-Dangerous]

  Definitely need power brakes though - it's harder to stop than the Coronet was!

Jeff, good to hear it's running right now.

My '70 had upgraded disc brakes in the front, but the brakes were manual. You need to go to the gym and build up your right quad muscle in your leg. Seriously, if I ever had to stop that car on a dime, I would be toast.

Good luck with it. I'm so happy for you!

[YellowThumper]

@ViperMan
To answer kit and $$$ v/s home brewed.
Either way you will be into it with a few hundred.
Overall it is easy.
My setup is pieced together with Mustang (mid 90s). They came on the models that had the huge mod motor because of space issues.
I did a lot of JY searching and checking. All the hydroboost units were essentially identical regardless of car make. I assume all are from same manufacturer.
Mustang, Chevrolet Suburbans and Astro vans, Ford, Dodge and Chevy heavy duty trucks also. Most all differences (minor) were in the mounting plates to firewall. The differences were only to firewall bolt spacing. The fore and aft distances were all the same. Just like the actuator push bars. Our firewall has 4 or 6 holes already for the manual or power versions.
Two of the existing firewall holes aligned with the factory mounting plate. These I direct bolted thru firewall. The others are combination of mounting plate and firewall bolting.
Also if I remember correctly all the push shafts were same general lengths. Only differences were the "eye" diameters. All I believe were larger than our cars pivot shaft. Simple bushing could be made to fill space.
My setup is aby normal as I retained my original p/b pedal bracketry under dash. Factory p/b use a short pivot arm that moves rod higher up. Utilizing this I had to cut and weld my pusher shaft (rod behind hydroboost or master cylinder) to be shorter. This raised mounting of everything for my turbo header clearance.
Normal setups will use similar adapter plate and push shaft will not have to be cut shorter.
To seal adapter plate is just a rubber sheet for a gasket. IIRC it was 3/32 thick.
Pressure hoses are obviously custom. Pressure from pump goes to brake booster first (safety issue) then it feeds the p/s gearbox. Hydroboost drain and gearbox drain just T together and go into pump normally. T is only a brass fitting with 3 hose barbs screwed to it.
For the hard lines the new master cylinder uses the bubble flair. I purchased lines with this flair already on them. Bent and cut other end to length and added our standard double flair to the other end.

Mike.

[Chryco Psycho]

Great info , Thanks 

[Bullitt-]

My 98 GT has hydroboost..a quick google turns up plenty of used units on the market..  $200 seems reasonable to me.  Imagine any decent scrap yard would have a selection on hand

https://www.ebay.com/itm/1996-1998-Ford-Mustang-Hydroboost-brake-System-Booster-Master-Cylinder-w-Lines-/182065104257

[Chryco Psycho]

Rock Auto has them for $130 without the master tho

[YellowThumper]

To further add.
Looking at picture. You can see that the firewall mounting plate is angled. This particular assembly mounts at an upward angle. The M/C reservoir accounts for this so top opening is horizontal. Again this is the firewall plate only.

And... on the Mustang hydroboost unit, the unit is rotated so the cylinder on it is toward the top. Dont know its purpose but all have this and most are rotated to lower side. 180 deg rotation. Same unit just rotated.

[YellowThumper]

If I was to attempt it again and "normal"
I suggest the astrovan (parallel mounting) and test to see if the later dodge plastic reservoir master cylinder or similar would mount correctly. From what I recall, all the 2 bolt mounting master cylinders had the same bolt pattern. I only recall 1 being different and it was from a Ford VERY heavy utility box truck. Its m/c was larger bolt spacing with also larger pistons inside.

[Brads70]

If I was to attempt it again and "normal"
I suggest the astrovan (parallel mounting) and test to see if the later dodge plastic reservoir master cylinder or similar would mount correctly. From what I recall, all the 2 bolt mounting master cylinders had the same bolt pattern. I only recall 1 being different and it was from a Ford VERY heavy utility box truck. Its m/c was larger bolt spacing with also larger pistons inside.

The one I have is off an astrovan , firewall mount was on an angle though. I removed it and started on making my own but never finished yet....