[Formulabruce]

Blower Defogger I have seen in base model 70's with the chevy engine sold in Maryland and Rhode Island.
I'm sure it all could be ordered, but only a 1970 could use this elaborate air recirculation. These didn't really demand much that the stock alternator couldn't handle.
Ramairnacho... the 27si Alternator is Much bigger , heavier, than the 10si, 10DN, and 12si " common" alternators. This did NOT show up till 1971 when the electric grid showed up. These alternators were NOT adjustable and the brackets Fixed them firmly in place on the engine.
The blower type defogger in '71 was shared with the X body cars ( V 2, Apollo, Nova) and probably a million others as the package trays got standardized.

[Ramairnacho]

Originally Posted by Formulabruce

Blower Defogger I have seen in base model 70's with the chevy engine sold in Maryland and Rhode Island.
I'm sure it all could be ordered, but only a 1970 could use this elaborate air recirculation. These didn't really demand much that the stock alternator couldn't handle.
Ramairnacho... the 27si Alternator is Much bigger , heavier, than the 10si, 10DN, and 12si " common" alternators. This did NOT show up till 1971 when the electric grid showed up. These alternators were NOT adjustable and the brackets Fixed them firmly in place on the engine.
The blower type defogger in '71 was shared with the X body cars ( V 2, Apollo, Nova) and probably a million others as the package trays got standardized.

Then with that being said the 904 was intended for car with ac and electric grid defroster? So
The 904 was only on paper? I have seen 1969 61amp alternators and they are normal in size, 10si I think. Im.still learning and yep confused like I was on #12 and #13 heads on an automatic ram air 3 formula. I yet to.see pics of a 904. But if a 903 will.do there job I'm running it. I just won't have date correct on that or starter but everything else is good engine size. I probably will never use the blower since I only plan I driving it in summer.

[unruhjonny]

/\ I believe that in 1969 the only internally regulated alternators were on the Corvette;
The rest were still externally regulated.

Most 1970 model year vehicles still received an externally regulated alternator - the Corvettes and V8 Firebirds but two of few models to have this - I believe that most if not all Camaro's still used an externally regulated alternator in 1970.

Ok, I will share something akin to what make some people here irritated with me - speculation;
It is my belief that this "open face" design (which was only seen on the earliest internally regulated alternators) was probably done for cost savings:
My hunch is that within the first couple years, that servicing proved that these were a problem, at which time the front face was redesigned for a stronger unit.

I say all this to try to punctuate the fact that you seem to be spending a whole lot of time (at least on this forum!?) chasing down parts which probably 85% of the people who will see your car will not notice as being out of place.

[Formulabruce]

Originally Posted by unruhjonny

/\ I believe that in 1969 the only internally regulated alternators were on the Corvette;
The rest were still externally

69 TA had a open face Si type ( would be later in model year)
These alternators are impo$$ible to find these days.

[Ramairnacho]

Originally Posted by unruhjonny

/\ I believe that in 1969 the only internally regulated alternators were on the Corvette;
The rest were still externally regulated.

Most 1970 model year vehicles still received an externally regulated alternator - the Corvettes and V8 Firebirds but two of few models to have this - I believe that most if not all Camaro's still used an externally regulated alternator in 1970.

Ok, I will share something akin to what make some people here irritated with me - speculation;
It is my belief that this "open face" design (which was only seen on the earliest internally regulated alternators) was probably done for cost savings:
My hunch is that within the first couple years, that servicing proved that these were a problem, at which time the front face was redesigned for a stronger unit.

I say all this to try to punctuate the fact that you seem to be spending a whole lot of time (at least on this forum!?) chasing down parts which probably 85% of the people who will see your car will not notice as being out of place.

You might be right and thank you for advice. It's taken me 1 year to. Fix mistakes and theft that happened to my car over the years. From.have to locate correct date coded heads, carb, water pump, distributor, starter, alternator and I enjoy learning, need tosay guages too since I didn't have ralley. You guys help me alot with info, I m not sure how many formula left out there with real ram.air still from factory but I guess that's what makes me want it for the most part number matching. I hope I didn't bother by asking about the alternator 1100904 but I never seen one. I found out that if you had rear defog only you got a 903 guess the 902 wasnt enough power. And hope that my unit still works. I got aways to.go.with my old car and someday I'll drive it again. Maybe the original style alternators are a bad design im.not sure but all the input helps.