Hello all, I'm new here. I just bought by first 1987 D150 /6 1brl. I've done alot of reading in the posts an exhaust mainfolds. I still have an unclear anwser as to whether the collectors are all the same diameter. I heard that the 1brls are smaller/there all the same??? I do know that when I had mine off the other month to replace the manifold gasket, I measured the inside dia. and it was about 1.7 something. I know it wasn't 2 inches. Can I go ahead and still use this ex. manifold with the 2 brl? This is a daily driver. I'm just looking to get alittle more out of it without big expense. I don't mean to sound cheap, this a back and forth to work truck. I already have the carb and intake. I do plan on getting a new exhaust system here shortly. Thanks for any advice here.

The only major difference between any of the manifolds is the choke pocket. Internally they are all the same.

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