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1981 F150 Ranger stepside - what spline count?

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Pete Whitstone

1981 F150 Ranger stepside - what spline count?

Was the spline count on the rear axle standard for this year, or did it vary based on towing package, rear end ratio, or other factors? Trying to figure out if my truck has 28 or 31 spline. Or something else... :) Thanks!

81 F150 Flareside, Edelbrock Pro Flow4 FI, hydraulic roller 351W, E4OD, 4x4, BW1356
92 F150 RCLB 351W E40D BW1356 mostly stock

Rusty_S85

Re: 1981 F150 Ranger stepside - what spline count?

Pete Whitstone wrote

Was the spline count on the rear axle standard for this year, or did it vary based on towing package, rear end ratio, or other factors? Trying to figure out if my truck has 28 or 31 spline. Or something else... :) Thanks!

Ill have to check but I think the parts and illustration guide indicates the trucks had a 31 spline rear axle. I know I looked it up myself to see what it should be to buy the same spline currie center chunk.

"Old Blue" - '56 Fairlane Town Sedan - 292-4V, Ford-O-Matic transmission, 3.22:1
'63 Belair 2dr sdn - 283-4V, Powerglide transmission, 4.56:1
'78 Cougar XR7 - 351-2V, FMX transmission, 2.75:1 9inch
"Bruno" - '82 F150 Flareside - 302-2V, C6 transmission, 2.75:1 9inch, 31x10.50-15 BFG KO2

myrl883

Re: 1981 F150 Ranger stepside - what spline count?

Yep, they're all 31 spline. Even my swiss cheese frame '81 F100 with 5 on 4.5" wheels had 31.

Ford Parts Monkey since 1985
1981 F100 Flareside - Black, 302-4V Roller/AOD
1986 F150 Flareside - Medium Fire Red 302/AOD
1989 F150 Standard Cab 4x4 - Dk Shadow Blue 302/AOD
1993 F350 4x4 Crew Cab - 7.3 IDI/ZF-5
I think it's a sickness...

ratdude747

Re: 1981 F150 Ranger stepside - what spline count?

Yep. AFAIK, at least with the 8.8", the only 28 spline units were found on 1990+ Rangers (4.0 only), explorers, Aerostars (also 4.0 only), Bronco II's (maybe, and Fox bodies. Everything else (F series, E series, and Broncos at least) is 31 spline out of the box.

1984 F150: 300 L6, AOD, RWD. EEC IV / TFI, Feedback Carter YFA Carb. Stock everything but radio (for now).