69 RoadRunner. I am removing the relay style Voltage Regulator and installing an electronic one like is used on 70 and up cars. The 70 model has an adapter bracket and the 71 mounts the regulator directly to the firewall. Will the 70 bracket fit in the mount holes I have or will I have to weld and re-drill? The current hole spacing is 2 3/4"

mine fit on my 68 Charger

Are U are aware that most of the replacements for the early VRs are actually electronic not mechanical..

Just my $0.02...

^^^ agreed, if the parts house "box" reg does not have the easily visible wire wound resistors on the bottom side of it then it is an electronic version which is vastly superior to the old electromechanical (OE) types. If you have a 2 field terminal alt which you would have to have to be swapping in the later "flat" reg with the triangle connector then just ground one of the male alt field terminals to the nearby alt case (or rework the brush holder to ground it for a more aesthetic appearance).

I will be installing this with a Gen III Alternator, which I have some wiring directions for. I would prefer an original style case with the electronics in it, but I don't know how it will behave. I am open to any workable options.

A guy on here mrrandyj used to sell an electronic one with the OE black case for $29 to your door & reportedly there are a brand or two of parts house regs that the OE black cover will fit right on. More info on the alt you have in mind as that is the wild card right now (is it the std big batt terminal/2 male field terminals?)

Just use the stock alt if good with a new style reg.Most the old points type case even covers them.No wires to cut or add just bolt in place of old reg.Ran them in at least 3 cars with the old alts and no problems.Unless you have tons of add ons no need to change alts.Rocky

It is a Gen III 5.7 2008 truck alternator. I don't know if that is considered a "big batt terminal/2 male field terminals" alternator. I believe our choices were Bosch or Nippondenso. What are they?

Buster
If you wiring is still stock, that alt will probably put out to many amps for your wiring. If its stock be care full, burnt up wires are'nt fun.
barracudadave67

a "regular" type alt which I am assuming it is (as far as wireing schematics go) as opposed to a 1 wire alt.