Q:Early to Late 205

[special-K]

What year did the late pattern/fine spline NP205s start being used?I`m looking at a 4spd/205 combo billed as late 80.I`m not sure if the guy means late`80 or late`80s,as in after mid`80s.But,wasn`t it later than 1980?Just want to know before getting back to him.

[1969 GMC]

Tim, I have heard '84 and '85 both when referring to the switch to 32 spline. The 1980 should be 10. Either way, it is easy to tell the difference between the two when looking at them...the 32 spline has the round pattern with the long adapter, 10 spline is the figure 8 with the shorter adapter.

[special-K]

Thanks Adam.I saw this on Craigslist near me for $150.There`s just one picture and it`s all still coupled,435/205.But,this is enough to know when I ask him to clarify what he meant by late-80.Since there were no changes in`80 (which I figured) I was assuming he meant late-80s.

[Americanrider]

All GM NP205 cases 1971-1985 had a 8 bolt "racetrack" bolt pattern

All GM NP205 Cases 1986-up had a 6 bolt circular bolt pattern

Input Spline: GM Used four different input shaft configurations on these cases.

10 spline: (1971-85) The most common were units supplied with a 4 speed which typically had a 10 spline male input shaft.

27 spline: (1971-79) The units supplied with a T350 automatic have a 27 spline male input shaft.

32 spline (Short); 32 spl (Long): The units supplied with a T400 Automatic (also SM465 86-up) have a 32 spline female input. We have seen both a short (about 1.5 to 2.0" stickout) and long (more like 3-3.5" stickout) versions of this gear. This gear is directly compatible with the Klune-V Extreme Underdrive, which can be supplied with a 32 spline output shaft. Longer spacers are required with the long input.

1979 to 1985 GM NP205: 8 bolt "racetrack" bolt pattern:
During these years, the GM NP205 showed up behind Turbo 400 and SM465 Transmissions in 1 Ton trucks only.. 1/2 and 3/4 T trucks began to be supplied with the NP208 instead. SM465 units will still typically use the 10 spline input. Turbo 400 units have the stout 32 spline female input (in most cases the short 32 spl input, about 1.5-2.0" stickout) however still uses the 8 bolt "racetrack" bolt pattern.

1986 and Later GM NP205: 6 Bolt circular bolt pattern:
At this point GM updated the unit to use the same 6 bolt circular bolt pattern used on the NP208, and all subsequent GM full size 4x4 truck applications. All of them are the 32 spline female input, although those we have seen are the long (about 3.5" stickout) 32 spl input.
Front Output

GM used two front output shaft configurations, one had a spline count of 10, the other was a 30 spline. 10 splines came before 1977 (roughly) 30 spline shafts came after 1977 (again, roughly). One quick way to tell them apart is by the fact that 10 splines came with a 1310 series yoke output, capable of accepting a CV or yoke driveshaft. 30 spline shafts came with the flat flange on the output, capable of accepting the GM 3R series CV joint.

The 10 spline output will accept the stock 1310; Or a separately purchased 1330 or 1350 Spicer u-joint yoke, and the 1310 CV yoke. The 30 spline flange will accept the 1330 or 1350 CV joints.
Rear Output

The most popular version Is a 32 spline shaft / fixed yoke and will accept a 1310, 1330, or 1350 u-joint yoke, and the 1310 CV yoke. Some were slip yoke, with a longer tailhousing.

[special-K]

Thanks Boone.This is FAQ material here.How about the 205 from behing the 3spd manual in 70-72s?I was told the input shaft was a different length than the 4spd configuration.But,after seeing your info I`d believe the difference is in the adaptor.Makes more sense that way.