7.5" Rear, 200-R4 Stock, with a 305 in front

Gonzo1970

Gonzo1970

Master Mechanic
Supporting Member
Sep 30, 2018
255
264
43
#1
Welp, after quite a bit of research I think I am going to go get a 28 spline Auburn Carrier, Moser 28 spline axles, and 3.73's for my stock 7.5" 10 Bolt while the 305 is in front of it. Total cost: Around $800.

I wouldn't mind going to a 8.5 but they're proving to be pretty scarce, and if you Can find one, they're around $1,200-$1,400 Used, and lord only knows if they've been beat to shit.

Point being, I don't think I am going to be near 300HP/TQ anytime soon.. The 305 in it is perfectly fine, and runs like a top. All I'm going to do it is letting it breathe.. an Intake (Edelbrock Performer with EGR (I can block off later, maybe)) and headers/duals.. At best, being Generous, I will be around 220-230HP, 260-270TQ.

The 7.5 with (or without, for that matter) the above mods should handle that with no issues, as should the stock 200-R4. What I am reading is 330TQ for the 200-R4 is its limit, and the 7.5 rear - 375 without slicks and slamming the shit out of it.. I don't abuse my cars. It might see the track once, maybe twice for shits and giggles (15.5 if Im lucky), but its a daily driver first and foremost, and lets face it, I'm not going to win many races, if I did race, with a "breathing" 305.

Logic here sound ok ta ya'll? Thoughts?

Thanks!

-Gonz
 
1bad79

1bad79

G-Body Guru
Dec 3, 2011
751
539
63
Allendale mi
#2
The 200-4r when built correctly can handle way more torque than that,in stock form not so much,I run one behind my aluminum headed 455 olds but it was expensive to build,but I like it and it was a fun project
 
lilbowtie

lilbowtie

Royal Smart Person
Jan 7, 2006
2,440
2,192
113
Canton Mi
#3
If your going to spend that much - a little more and you have something. But -yes it will work.
 
Kwik_Cutty88

Kwik_Cutty88

Moderator
Moderator
Nov 22, 2011
1,076
441
83
Coastal North Carolina
#4
You should try to find some used 8.5" axles from a Grand National or 442. They bolt right in. Sometimes you can find a good deal on used 28 spline carriers on eBay.
 
Wraith

Wraith

Royal Smart Person
Jan 13, 2013
1,046
2,570
113
DFW, TX
#5
Nothing wrong with the 7.5" if you ain't beating it like a 16 year old trying to be John Force. I used to drive mine like that but always made sure it didn't/wouldn't hook it hard from a dig.
 
melloelky

melloelky

G-Body Guru
Oct 22, 2017
870
1,283
93
mass
#6
keep sticky tires off it and it'll last longer.
 
83StreetMachine

83StreetMachine

Apprentice
Dec 16, 2011
91
87
18
Central NJ
#7
Gonz, where are you located?
 
Gonzo1970

Gonzo1970

Master Mechanic
Supporting Member
Sep 30, 2018
255
264
43
#8
wskirvin

wskirvin

Greasemonkey
May 22, 2017
140
135
43
Indianapolis, In
#9
The 200-4r when built correctly can handle way more torque than that,in stock form not so much,I run one behind my aluminum headed 455 olds but it was expensive to build,but I like it and it was a fun project

Who rebuilt your trans? i'm planning on running one behind my 455 as well.
 

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