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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: cwest on July 07, 2014, 02:54:43 pm

Title: Will the TH400 out of my 86' fit onto an 88'?
Post by: cwest on July 07, 2014, 02:54:43 pm

I've got a TH400 out of an 86' K20 which was coupled to an NP208 on the market.  A guy was asking me if it would fit onto his 88' truck.  I know 88' is a body style change year but did they stick with the same automatic trans and transfer case setup?  The trans I'm selling is a 32 spline output.  I'm hoping it matches with this guys truck.

Title: Re: Will the TH400 out of my 86' fit onto an 88'?
Post by: Irish_Alley on July 07, 2014, 07:32:19 pm

yes but it should be a different length so you might be able to use your old shafts if the bed length is the same but then you have the ifs to deal with is his 4wd? is it a reg cab?

Title: Re: Will the TH400 out of my 86' fit onto an 88'?
Post by: bake74 on July 07, 2014, 07:55:31 pm

     The TH400 was used up till 1992 on certain models.

Title: Re: Will the TH400 out of my 86' fit onto an 88'?
Post by: cwest on July 07, 2014, 08:01:14 pm

Was there any kind of a spline change between the models years?  If so, are splines easy to swap out?

Title: Re: Will the TH400 out of my 86' fit onto an 88'?
Post by: pholliday1 on July 08, 2014, 08:13:45 am

Splines are the same, where you run into a problem is with swapping transfer cases as cases that came behind the 700r4 only used 28 splines. Th400 was extremely popular in 88 even showing up in production 1/2 tons.

Title: Re: Will the TH400 out of my 86' fit onto an 88'?
Post by: Irish_Alley on July 08, 2014, 10:51:44 pm

correct me if im wrong but 88 was the year gm changed to IFS so the t case would be on the wrong side( except for blazers, crew cabs and suburbans) like pholl said the splines are the same (32) the 4l80e (1991) even used the same splines. but more than likly its a 4l60 (700r4) so its a 27 spline