I'm trying to find out if my 205 has 10 or 27 splines without pulling it. It's stock in my 70 blazer behind a th350 with the stock adapter. I appreciate the help.

27 spline all th350's are 27spline same with 700R4's 10 splines are in the 465/205 combos

27 spline for sure only the 465 came with 10

the np205 was never offered with a 700r4.

it can be adapted.

I appreciate the replies. Just curious did the next gen,73+, still use the adapter between a th350 and the 205 like mine? That's what was screwing me up, for some reason I though that they were all 10 spline in 70. I almost bought the wrong part, thanks guys.

th350 adapters are externally the same from 68 to 83. a th350 is a th350... four bolts to bolt the adapter to the trans, 8 bolts to bolt the adapter to the case.

there is an internal difference.

on some adapters, there is a bearing that supports the sleeve and keeps the seals happy. sometimes, the bearing goes out, and makes a hell of a racket. most of the time, the seals go out, and the bearing gets more than one kind of lube.

the 700r4 are 27 spline tailshafts just they are longer by 2" thats where the adapter comes into play but you can also swap out the tailshafts with a th350 tail shaft and the np205 from a TH350 bolts right on

I already swapped in a 700r4 using a shaft from advanced adapters. The only thing left to rebuild is the transfercase. I am just looking for a cheap one that I can rebuild so I don't have to park my truck while i rebuild it since it's my dd right now.

yup i run a bowtie overdrive stage 2 700r4 with a 205 fixed yoke

I have a few more questions if you guys don't mind.
Can I get away with just replacing the seals on the adapter? Anyone know the part numbers or a good place to get them?
If I bought this kit, Rebuild kit (http://cgi.ebay.com/ebaymotors/Complete-Master-Rebuild-Kit-NP205-Transfer-Case-205_W0QQitemZ300221658329QQcmdZViewItem?hash=item3 00221658329&) anything else I need besides the adapter seals?
What does the average at home rebuild cost? I'm trying to decide if it makes sense cost wise to rebuild it myself since you can buy one rebuild for around 400.00 with no core charge and a warranty, 205 (http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=280223921676&ssPageName=STRK:MEWA:IT&ih=018).
What do you guys think?

The case is stupid simple to rebuild yourself. Everything is retained with standard SAE bolts or snap rings. Some of the snap rings will take some effort so make sure you have a decent pair of pliers for that, but otherwise it is very straightforward. The only part that will be difficult to do at home is to check for endplay. If you use the original shim stack you should be ok, but it really would be a shame to rebuild the case and not check it. Any shop with a press will be able to do that much for you.