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Thermactor Pump and DSO?

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Old Jun 8, 2004 | 01:22 PM
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Thermactor Pump and DSO?

Just bought a 75' F100. It has a 302 V8 and automatic transmission. The whole truck looks to be original as I have found the "OK" stamps still visible on both fenders, and the fact that it still retains it's "Army" green exterior and interior leads me to believe no one has ever re-painted it (I would think the color would have definately been changed if so.........

Anyway, aside from the body being pretty solid for this area (Illinois), a couple other things have me wondering if this might be a west coast truck originally? The door tag says the DSO is 46. Anyone know what area that is for? And also, the engine still has the 1975 emission sticker on it, but there is a smog pump attached. I thought these were introduced on truck's in 1979, but have heard that California emission truck's received them much sooner. So, the DSO makes me wonder, and the pump being attached to the engine also has me curious.

One last question, what would the rear be in this truck? I know it's a 9", but would it be 28 spline like for a car, instead of the larger F150 31 spline type? The door tag has 17J as the axle code, but I can't find the reference for this code, so maybe it's stamped in the wrong place or something.........

Anyway, thanks for any assistance.
 
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Old Jun 8, 2004 | 03:46 PM
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My 77 F100 has a 302/C4 and it is 31 Spline. My 77 F150 is also 31 spline.
I had a 78 That had a 300/C6 that was a 28 spline.
 
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Old Jun 8, 2004 | 04:03 PM
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DSO code 46 is Indianapolis. The Ford manual lists a thermactor(air pump) check on the 1975, 1976 maintenance schedules. Code 17 for the rear axle is a 3.25 axle ratio. I am assuming you have a 4WD since there are two axle id codes. The 'J' identifies the front axle code, but I can't find the id for the front axle. If you don't have a 4WD, then, apparently the cab is from another truck.
 

Last edited by fatherdoug; Jun 8, 2004 at 04:14 PM. Reason: need to add more information
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Old Jun 8, 2004 | 04:51 PM
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A DSO of Indy, huh? Well, that's the right area, so I guess it's not a Cali truck. I've owned (2) 78' F150 4x4's that did not have the air pump on them (they had their original engines). The 79' F150 4x4 I own now, did have the pump - I took it off when I swapped in the 400 a year ago. I always heard car's got the pumps in 78', and truck's were a year later. Guess not. I was reading another thread about axle tag ID's, and someone replied that the J stood for power steering, which this truck has. The cab is original, as are the doors - as the VIN matches the truck's title. The door tags are what the information is stamped on concerning this truck. The cab tag has month and year of build and some tire information only. Well, a 3.25:1 gear would be great if that's what it is.

Thanks!
 
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Old Jun 9, 2004 | 06:19 AM
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Keep in mind that the F-150 was exempt from some of the emissions regulations for a period of time because they had a gvw greater than 6000 lbs. The F-100 would have come under the same guidelines as a car during the mid 70's.
 
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Old Jun 9, 2004 | 06:22 AM
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Ahhh, that does make sense. This is the first F100 I've had. First 2wd truck from the 70's for that matter. That's understandable on the GVW though - Good Point.
 
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Old Jun 9, 2004 | 07:28 AM
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All,
Correct me if I'm wrong,
If it had a cat on it, it would have had an air pump? True or False?
If it had the "unleaded fuel only" on the fuel gage, then it had a cat?
What your telling me is that only the F100 had the emissions equipment before 1978? I have only ever owned F100's and thought all trucks had emissions controls. I just started buying F150 a couple of years ago and they are 78s, They have some emissions equipment left on them (no cats).
Even a blind sow finds an acorn, now and then,
KingFisher
 
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Old Jun 9, 2004 | 12:32 PM
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I would say that is true for '78. My experience is limited to '78 or '79.
My 1979 F-150 also required unleaded fuel, and contained a catalytic converter and air pump. My 1978 F-150 has neither, and was purchased that way new.
 

Last edited by fatherdoug; Jun 9, 2004 at 12:34 PM. Reason: more info
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Old Jun 9, 2004 | 04:35 PM
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One of my 78' F150 4x4's did have the air pump. I remembered this last night, as I had to have RH head plugged when the heads were rebuilt (burnt valve). The other 78' didn't have it though.............
 
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