The 301 doesnt have the required mounting holes so they used adapter plates with the bonnie mounts. Rock Auto has the Bonnie mounts for $10.  

Awesome thanks for all the replys appreciate it.cars pretty tough was hoping to get it moving under its own power to get it to body shop and start tear down then was gonna worry about doing a better drivetrain setup.at this point I think Ill just toss one of my ls engines in seeing as Ill have to do same amount of work to put a sbc

Big Bear wrote:

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Transmission has BOP bolt pattern and wont bolt to Chev

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 Good point, unless by some slim chance it has a dual bolt pattern case in it. Odds aren't great though.

I have several good running 350 Pontiacs still in cars that you can hear run You can reach me at 905-518-5264

I think it would be easier in the long run to put a Pontiac engine back in the wagon. I'd take Roundport up on his offer for at least a 350.

The challenge with a chevy engine in that car is that unlike the A or F bodies or even the 71-76 big cars the 65-70 that all use corporate GM frames the 65-70 big cars all had their exclusive frames with no sharing between divisions. If you want to put a chevy engine in say a 69 GTO you just get a set of chevelle engine mount brackets and they bolt in to the frame because all A bodies shared frames across divisions. But a pre 71 big Pontiac has a frame that was engineered to receive only the pontiac engine. Chevy mount brackets won't fit and the cross member (pontiac had two in the engine bay) may be in the way of the chevy exhaust dumps. You can always make it fit but it will be a pain and a butcher job in the end. A Pontiac 400 or 428 would be easier, cheaper and add rather than detract from the final value of the car.

For anyone interested I have 5.3 ls installed in wagon didnt have to cut anything just drilled 4 holes for chevelle mounts so its straight bolt in setup and can be removed anytime tk have Pontiac engine put back in if wanted

It looks like I am a little late to this one, but I hope to still be of assistance to 'slow69', or anyone else who might come across this in the future;

Pontiac-USA had different motors that Pontiac-Canada;
For the most part, Pontiac-Canada used Chevrolet drive trains.
What you're looking at is a Pontiac-USA car that had a Pontiac V8 engine in it from the factory (some Canadians have previously lumped, Oldsmobile, Buick, and Pontiac V8's as "American Big Blocks").

The 1969 & older Pontiac V8 blocks were casted with one engine mount boss style, while 1970-1975(?) Pontiac 350/400/455's were casted with dual motor mount bosses;
Some time around 1975 the earlier motor mount bosses were removed from the block castings, and what you have there is an adapter plate that was intended to mount a later 350/400/455 into an earlier car.
I would guess that your car has the correct style engine mount intended for that car, but the adapter plate was used to make a later block work with the earlier mount.
(The Pontiac 265/301 were short deck versions of the earlier 1955-1978 Pontiac V8 which was never casted with the dual engine mount bosses.)

If you ever decide to put another Pontiac engine into your car, you may have to use those adapter plates again - unless you find an engine that has the earlier, or dual engine mount bosses.