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I have a 67 fastback that originally came with a 390 and a 4 speed. Unfortunately somewhere along the way someone pulled the original drivetrain and it now has a 289 and an automatic. Here's my dilemna and a possibly stupid question. Do you have to have the original motor for the numbers to match, or could I use any motor built within the same model year. I actually have a 390 that I bought on a whim for cheap years ago, but I think it was from a later year truck. Lately I have been thinking of going more of a restomod route and put in a T-5 and a small block of some kind. I'm not really interested in trying to make a concourse car out of it, but I might like to try and get it close to being original. Overall I want a great classic Mustang that I can drive on nice days, but the cost of a big block may be prohibitive. Any opinions?

By the way when they took out the toploader and put in the automatic tranny they left most of the clutch pedal assembly and just tucked it under the carpet. Lucky for me I guess.

Thanks for your input,

Brian aka hecubus
 

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Make it a '68 coupe and im in the EXACT same dilemma. Mine ran a 390 once upon a time, but now runs a "D" code 289 . Considering it WAS a 390, and that the car hasnt been used as a donor, most of the stuff required to use a big block should be there, so very little modification, if any, would be required. However, you would need 390 motor mounts, which i believe are very hard to find. I dont know exact details of the "S" code engine, but it is the exact same as the GT 390 engine. Cant help on the manual-auto-manual as mine always ran an auto, so i havent looked into that.

Oh by the way, the 390 out of a truck you have, i have *heard* that the compression ratio could be different, but i dont know what the he!! that means /forums/images/icons/laugh.gif

Gary
 

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The "matching numbers" are that the block, intake, heads etc. have the correct date code i.e. it should not be a C5 (65) or D0 (70) part number to be correct. so, you could use any motor built within the same model year and be "numbers correct"

That being said, even for concours street driven cars in a judged show, it is rare for most judges to check for part numbers having the correct date stamp. You will only get points taken away if the part is obviously different than what was correct for that year. Thoroughbred cars definitely have to have the correct year parts.
 

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I was lucky and the frame mounts were still on my car when I got it. I got the rubber insulators straight from ford last year and the engine plates from a mustang specialty shop in calgary. Toatl cost around $300 Canadian.
 

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I am currently doing this swap, and it isn't all easy.
I went from a 289 C4, to a 390 C6, numbers aren't a factor for me, i just want something that runs and looks good.
The rads are different. Engine mounts and frame mounts are similar, but need to be slightly modified for the big block. I needed to find a transmission crossmember for a C6. driveshaft for a C6. Exhaust manifolds for the Mustang/Cougar/Failane. Power steering brackets for Mustang/Cougar/Failane. Cylinder heads for the same.
Items like the pwr steering brackets, heads and ex manifolds will all fit any 390.........but they won't all fit the Mustang body, and they need to.
I live in Canada, there isn't a lot of places to find used Mustang parts that are affordable. Learn from others that have been on the same road, let them make the mistakes and then ask them for the answers.
 
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