Driveshaft won't fit

I have a 1988 Mercury Grand Marquis with a 5.0 and automatic overdrive. The transmission went out and i replaced it with one out of a 1989 crown victoria and now I’m having problems on not getting a driveshaft to fit. I realized that the tailshafts between the old and new transmission were different and the newer one was longer. The one for the grand marquis is about a half inch too long so I got one that was off of a transmission with this longer tailshaft and this one is about an inch longer. Is there a way to get one of these to fit without too much modification?


I’m all for DIY as much as possible but this might be one example of when you should let the pros do the work. Your local driveshaft shop can do anything from replacing the tailshaft with one that will work to changing the length of the main shaft to make it fit. Last time I had a shaft altered and completely RnR’d it was about $150. All you need is a length change and re-balancing so it should be reasonable. Stop in with your measurements and see what they’ll charge.

What TT said. but I’d take the driveshaft with me to show them.

Are the front yokes the difference? If different, maybe they could swapped as it’s likely the U-joints are the same.

Other than that, modifying driveshafts (cutting, etc.) can be a bit iffy and it’s often best left to the driveline pros who have the proper equipment to modify and balance them.

You have put yourself in the Twilight Zone…Ford changed the tailshafts AND the wheelbase in '89 so finding a drop-in shaft for your '88 will be difficult. A driveshaft shop can shorten your existing shaft quickly and easily. Just get your measurements right. The slip-yoke needs at least an inch of free movement, maybe 1.5 inches…

In more modern large Ford Sedans the police interceptor versions have a shorter, aluminum or metal matrix composite drive shaft and a longer trans tail shaft so they can run at higher speeds. Town cars also have the longer tail shaft. You can do anything you want as long as you have matching parts. I don’t know if this applies to the 88-89 vintage, but you can find out at

OOPS, somehow I missed Caddyman’s first answer. It is much better than mine.

Town cars have a slightly longer wheelbase…It gets complicated…