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#1 |
Registered User
Join Date: Apr 2007
Location: Sandpoint, Idaho
Posts: 178
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Rockwell T221 - NP205 swap
Ok....I read as much as I could about what people did when they did this swap. I used the cross member that came from the donor because I read that it was 1"-1 1/2" lower so it wouldn't rub the floor of the cab. I installed new cab mounts and the t-case still hits the floor. My thought was to cut the floor and weld in a new "humped" piece that is 1" higher than the floor and sits under the seat. I have no pics as my truck is 30 miles away at my inlaws. If you have any better ideas, and no I don't want to go with a body lift, I would love to hear them.
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1969 Chevy K20 Custom Camper 350, 4sp, 33's High on plans, Low on funds |
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#2 |
Registered User
Join Date: Apr 2007
Location: Sandpoint, Idaho
Posts: 178
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Re: Rockwell T221 - NP205 swap
I know some of you have done this swap....I think I am going to cut the floor but any suggestions are welcome
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1969 Chevy K20 Custom Camper 350, 4sp, 33's High on plans, Low on funds |
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#3 |
Registered User
Join Date: Dec 2007
Location: Middleburg, North Carolina
Posts: 480
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Re: Rockwell T221 - NP205 swap
i made the swap this past summer...removed the 3spd/t-221 and replaced it with a 350 auto and np 205..i didnt have any floor problems.. maybe it was the auto transmission and cross member...
my suggestions would be to cut some 1" square tubing about 8" and bore holes and lower the corss member from the frame. that should get it off the floor board...s. |
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#4 |
Registered User
Join Date: Feb 2000
Location: Center City, MN, USA
Posts: 3,254
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Re: Rockwell T221 - NP205 swap
It sounds like you do NOT have a "high hump" cab. The low hump is part of the floor sheet metal. The high hump is bolted in. If it is true that your transmission tunnel isn't bolted in, just buy a high hump off the parts board, cut your low one out, and bolt in the high one.
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'70 cab, '71 chassis, 383, TH350, NP205. '71 Malibu convertible '72 Malibu hard top Center City, MN |
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#5 |
Registered User
Join Date: Apr 2007
Location: Sandpoint, Idaho
Posts: 178
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Re: Rockwell T221 - NP205 swap
I do have a high hump cab....the t-case is hitting after the hump near the seat. I thought about adding some square steel to the cross member to lower the t-case(and I still might).
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1969 Chevy K20 Custom Camper 350, 4sp, 33's High on plans, Low on funds |
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#6 |
Post Whore
![]() Join Date: Feb 2000
Location: Rose Hill, KS, USA
Posts: 12,684
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Re: Rockwell T221 - NP205 swap
What year was your donor vehicle. Very odd that your hitting the floor. I'm doing this same swap but I have a body lift so I don't have this issue. My thread is over in the 4x4 forum.
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1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14 |
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#7 |
Registered User
Join Date: Jan 2001
Location: Lincoln, Nebraska
Posts: 2,145
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Re: Rockwell T221 - NP205 swap
I bet you don't have the correct 4x4 cab mount bushings. In my original 67 4wd they don't use the tall bushings just the old 2wd style bushings in the rear. Check those against another 71-72 4x4 or even a 3/4 ton 2WD as they are the same. Might want to try this posting over in the 4x4 section.
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'66 CST BBW swb fleet 327 fac ac '67 CST 4x4 swb 327 stepside project '72 Cheyenne K20 50k original '72 Cheyenne Super K20 project '73 Sierra swb 4x4 frame off in paint stage '74 Cheyenne Super swb w/16k actual '71 & 72 Cheyenne K10 4x4 swb's '70 426 HEMICUDA conv SHAKER 4 sp Dana 60 '60 Impala conv 327 PG fac ac loaded 3rd owner '72 GMC K2500 4x4 '59 Apache CST BBW fleetside swb 283 '73 ElCamino SS LS1 T56 true SS bucket tach '76 ElCamino SS 52k survivor '87 Grand National 41k True 2nd to last built in 1987. '86 K30 454 SRW fleetside CA since new '88 Trans Am GTA 39k bought new 2018 DEMON plum crazy @ 840HP! "Need for speed" Last edited by HOTFUN; 12-06-2008 at 12:07 AM. |
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#8 |
Registered User
Join Date: Apr 2007
Location: Sandpoint, Idaho
Posts: 178
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Re: Rockwell T221 - NP205 swap
the donor was a 1983 chevy 1-ton. I got the tranny, t-case and drive lines. I know the cab mounts are correct because I called gmcpauls and confirmed which ones were correct. I also checked them with the originals. I want to say thank you for all the input. I think I am just going to shim the cross member down.
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1969 Chevy K20 Custom Camper 350, 4sp, 33's High on plans, Low on funds |
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#9 |
Back in the sticks
Join Date: Jan 2001
Location: Fordland, MO
Posts: 3,188
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Re: Rockwell T221 - NP205 swap
I swapped from a 3 speed to SM465 withe the Rockwell and I'm still pretty close to the floor too. Not touching, but pretty close. I have stock body mounts and haven't lowered the cross member yet, but may in the future. My rockwell is also behind the hump where it is close to touching, but I think this may be due to the change in tranny's.
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1971 Cheyenne C-10 w/700R4 and Tuned Port Injection 1969 K5 Blazer w/Tuned Port 2010 2SS/RS Flaming Orange Camaro 2011 K1500 Suburban 2014 K1500 Pickup 2008 Nissan Altima? The wifes' hoopty |
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#10 |
Registered User
Join Date: Feb 2000
Location: Center City, MN, USA
Posts: 3,254
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Re: Rockwell T221 - NP205 swap
I'd purchase a 67-72 NP205 cross member off the parts board. No shims and you know it will be factory correct - in other words some engineer in 1968 or 1969 figured out the drive line angles. Using a 1983 1-ton you're kind of rolling the dice.
FYI, ALL 67-72s that came from the factory with a NP205 shared the same cross member. So if the used part salesman says it was a 3-speed/NP205 or a 4-speed/NP205 or a th350/NP205 don't worry, my th350/NP205 is sitting on a 3-speed/NP205 cross member, the one that came originally with my truck. Back then GM made EVERY transmission in front of a NP205 bolt to an adapter that fit the same cross member. GM was doing modular design before anybody knew what modular design was.
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'70 cab, '71 chassis, 383, TH350, NP205. '71 Malibu convertible '72 Malibu hard top Center City, MN |
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#11 |
Registered User
Join Date: Apr 2007
Location: Sandpoint, Idaho
Posts: 178
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Re: Rockwell T221 - NP205 swap
The cab is sitting on the rear mounts and is less than 1/2" off of the front. I think I am going to shim the cross member 1" and go from there. I will get some pix posted when I get to work on my truck next.
__________________
1969 Chevy K20 Custom Camper 350, 4sp, 33's High on plans, Low on funds |
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Tags |
205, floor, swap, t-case, t221 |
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