283 th350 swap

[Marty68]

hello gentlemen.. I have a 51 gmc. with a 283 that appears to be 57-66. I have not been successful narrowing the mfg date down it is attached to what appears to be a bellhousing that belongs to the engine. its "code" indicates truck bellhousing. it has truck geared 4 spd. torque tube and I believe 4.11 gears. I am planning on s10 blazer rear. 3.42 gears. already bought and paid for.
I ordered then told him to hol off cashing check, for a th350 rebuilt non lock up long shaft.
is there any issues I should look at for pairing these together. I looked for flex plate converter bolt pack. transmission crossmember etc.
but browsing forums it seems I may have a bellhousing crossmember that will be an issue.
please guide.. or should I scrap the whole idea and find car 4 speed to bolt to existing bell housing?
I had thought about t5 s-1- but got super confused about what fits what doesn't... here are some pics.
Thanks for the help and advice guys

[Marty68]

maybe a better pic of engine code"

[Marty68]

better bellhousing pic.

[Marty68]

3849852....283...57-66...2
6263756 Aluminum, Truck, 12" Clutch, Big Hole, 5 Bolt Transmission, All Engines
aluminum bell may indicate block mounted starter.,
would I need "mid" engine mount I believe there is a crossmember on center of trans right now. my thought was remove it bolt th350 to engine locate and install premade crossmember a tail of trans.
again thanks for advice.
yes I know 700r 0r 2004r for OD but those are costly.

[geezer#99]

To use a turbo 350 you’d need to remove the existing bell housing crossmember.
Fab or find/buy a rear tranny crossmember.
Put a floor shifter in.
Kick down bracket.
Possibly dip stick mods.

A car type 4 speed would work.
It would bolt in to your bell.
Might need a spacer ring depending on tranny.
Shifter needed of course. Shifter placement can be tight to your seat.

Likely cheaper to go with the automatic.

[Marty68]

I just talked to trans rebuilder. he said rear crossmember would be fine. he sent a link to a spacer plate to adapt if block is unthreaded.
the floor shifters are expensive.. I have an idea on how to mount and raise a B&M ratchet shifter.
now to find ratty used one cheap

[geezer#99]

What does ‘block unthreaded’ mean?
Is your motor side or front mounted?

[Marty68]

apparently some??? 283s do not have threaded or drilled holes for a starter. if not there is a $130 adapter plate. it sounded like those were only truck bellhousings that were cast iron? and the starter bolted to the bellhousing unsure unclear.. the engine appears to be mounted to a "plate off top of frame very similar to how the 216 in my 50 chev car was. this is a question I need to find an answer to. trans guy says he has 700 hp drag cars running those mounts and just rear crossmember no mid mounts.
keep in mind he is selling me trans

[geezer#99]

He might have that set up but he’s only going a 1/4 mile at a time.
Front mounted motor and rear mounted tranny puts stress on the tranny to motor bolts.
If you need an adaptor for the starter at that price plus shifter and rebuilt tranny I’d just put a 3 or 4 speed tranny in it. Shifter is doable with a bench seat type shifter.

[geezer#99]

If you look around on here you’ll see a bell like this that has a starter mount and can use a car trans.
https://www.4speedconversions.com/3815891_1.html
I’m not sure if it would bolt directly to your present crossmember though.

[Marty68]

Originally Posted by geezer#99

He might have that set up but he’s only going a 1/4 mile at a time.
Front mounted motor and rear mounted tranny puts stress on the tranny to motor bolts.
If you need an adaptor for the starter at that price plus shifter and rebuilt tranny I’d just put a 3 or 4 speed tranny in it. Shifter is doable with a bench seat type shifter.

ugh...

[Marty68]

what is meant by mid mount? and front mount? is "front mount different than the triangle motor mounts? I think this has that to the block then it sits on a flat pad off frame... I will snap pic when I get home in half abot an hour

[Marty68]

Here is a pic of how engine is mounted and starter. "Not belhousing" starter.. Ilooks like bellhousing g bolts to the crossmember. Engine looks to be mounted where all small blocks are.

[Marty68]

Here is a pic of how engine is mounted and starter. "Not belhousing" starter.. Ilooks like bellhousing g bolts to the crossmember. Engine looks to be mounted where all small blocks are.

[Marty68]

Pics

[Marty68]

This normal mounts and trans crossmember? I wonder if this would just bolt to frame?https://www.speedwaymotors.com/AFCO-...ear,40453.html

[geezer#99]

your motor is indeed side mounted.
55-57 sbc was front mounted like in this link.

https://www.trifive.com/forums/showthread.php?t=105463

Appears your starter is block mounted. Would need a pic from the bottom to be sure.
No need for mounts like that in your speedway link.

[Marty68]

I will post pic in am. LOVE THIS TRUCK. just drove to next town 25 miles. To give a hug to my 20 yr old baby girl

[Marty68]

Motor mounts.. no crossmember under engine....
Crossmember under bellhousing. Rivited to frame.
Bellhousing NOT bolted to it.
Crossmember at tailshaft of trans bolted to frame.
Looks like bellhousing crossmember would have to come ot for room for th350.

[geezer#99]

Yup!
Crossmember out!
Tough crappy job!
Decisions! Decisions! Decisions!
Leave it alone till winter and enjoy it or start ripping and tearing!
Likely easier to pull the motor and tranny out completely to make it easier for crossmember removal.
You got a shop to work in?

[Marty68]

Removing that crossmember under belhousing looks to be a bad idea without first putting one under engine. So cancel th350 order? Rethink using a manual? Will this bellhousing work on what transmissuons? A t5 would be good.

[geezer#99]

You could use a mount like this for the motor.

https://www.tdotperformance.ca/trans...IaAsZlEALw_wcB

T5 has it’s problems too. Not a bolt in. Input shaft mods, shifter location, speedometer hook up.
And a tuff fit for the shifter and your seat.
Most Muncie or Saginaw car trans will bolt in better.
Some problems with them are shifter location, input bearing size, speedo hook up.
A lot depends on your budget.
Are you doing it yourself or paying someone to do it.
Are you the only one driving it?

[Marty68]

I have help. I am only driver... I eventually plan mII front. At that time I could do it all.

[Marty68]

Decisions decisions. I have a guy who is a dive welder.. who will do. MII stuff. May wait do all at once. Should cancel th350. Look for 4.8 4l60. Now my head is spinning.

[geezer#99]

I’m thinking blown 392 Hemi!
9 inch rear with 4.88’s.
4500 stall.
Zero to sixty in a heart beat.
2 mpg if I’m lucky!
Wait!
I’ve already done that!
It’s your truck!
Likely better to get all the stuff together, get a final plan, save a big bucket of cash and have a winter project!
Enjoy it as is for the summer.