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73-87 Chevy _ GMC Trucks => 4 Wheel Drives => Topic started by: koolray09 on November 14, 2015, 09:39:57 am

Title: adapter plate bolts - to transmission - where buy new ones ?
Post by: koolray09 on November 14, 2015, 09:39:57 am
I have a turbo 350 with np230 and requisite adapter plate.   Four bolts hold the adapter plate to the transmission.

these bolts are special in that they have - what looks like - a small shoulder where the threads meet the underside of the bolt head.
there is a matching circular indention in the adapter plate to match.

Where do I go to buy those bolts new ?
Title: Re: adapter plate bolts - to transmission - where buy new ones ?
Post by: werewolfx13 on November 14, 2015, 11:04:54 pm
Might try a dealership, I used ordinary grade 8 bolts on my 350/203 combo.
Title: Re: adapter plate bolts - to transmission - where buy new ones ?
Post by: koolray09 on November 15, 2015, 08:01:39 am
Dealership was my first call.  No luck.
Title: Re: adapter plate bolts - to transmission - where buy new ones ?
Post by: Blazin on November 26, 2015, 12:22:35 pm
Any hardware store will have bolts to fit your threads, & length. Grade 8 will be the best bet. Clean the holes out with some brake clean, maybe compressed air if you have a compressor. Use blue lock tight on the new bolts.
Title: Re: adapter plate bolts - to transmission - where buy new ones ?
Post by: 80Chevy4x4 on November 26, 2015, 12:53:23 pm
Fastenal carries all types of bolts and such.
Title: Re: adapter plate bolts - to transmission - where buy new ones ?
Post by: koolray09 on November 26, 2015, 04:26:41 pm
As it turns out...what I thought was a machined surface that looked like an o-ring, turned out to be an actual o-ring.  It is a sealing washer. AS you know, the adapter plate has a gasket where it bolts to the NP203 xfer case.  Those bolts, if not sealed will allow fluid from the xfer case to leak.  Turns out, nothing special.  just a bolt with a sealing o-ring - that can be replaced.   I will install new orings and sealant when I mount that adapter plate to xmission. 

I found this exloded view on another forum I was browsing... pay attention to item 7.