gear question

[5.0gt]

i recently bought a 1988 gt with a mildly built 5.0 it has 245 40 18 tires on it which is a 25.6" tire it has a stock 5 speed tranny, i want a rearend ratio which will still be a comprimise between good torque and good highway rpm i currently have a 3.73 ratio put in by the previous owner please let me know yer opinion                                   

[Bossnutt]

In the 5.0's we've had in the past we had those, 3.08's, and 3.55's.  Personally I like the 3.55's better.  They were good for torque and highway miles.  But it all depends on how people drive.

[5.0gt]

ok good i have a axles out of old f150 ive had both 8.8s one with 3.55 and one with 3.08s  i bieleive the ring and pinion are the same as my stang am i correct? i will keep my carrier w/ ls

[Bossnutt]

Your best bet is to keep the 3.73's with the 18" tires on there.  The axles are different in a f150 and a mustang.  They won't work.

[5.0gt]

arnt the ring and pinion the same being they are both 8.8s im not saying im right im just curious i would keep the 3.73s but 65 mph is 2700 rpm and that seems a lil high

[Bossnutt]

Actually you're right about the ring and pinion, it's the trac loc that has a different spline between the 2.  But the 65mph @ 2700 rpm is actually great.

[Soaring]

65 at 2700 RPM is great???  This guy is going to have to sell his soul to be able to buy gasoline for that hotrod.     My 03 Mach runs at 2000 RPM at 80 MPH with the 5 speed overdrive, and I get right at 26 MPG on  the freeway.  My 65 with a 2.73 rear is getting right at 20 MPG at maintaining a 75 MPH speed on the freeway.  Granted, it is a well tuned 289.  With 3.55's, and running 2700 at 65, I would expect him to see maybe 13-16 MPG.  Not good when you are paying over 4 bux a gallon. But, we didn't buy Mustangs for gas mileage anyway, did we?   

[5.0gt]

after driving it for about a week now 14 mpg isn't going to cut it im willing to lose some low end to get lower rpms on the highway other than that i love this car ive always wanted a mustang and now will never go without one

[Soaring]

I believe my nephew's 02 GT has something like 325 gears, and he gets over 20 MPG on the freeway in 5th.  The thing is, you need to change out the tranny and/or the gears to get up into the 20's.