The crossmember hoop is about 9" tall, 14" wide at the bottom. It's hard to see now because I just put some seem sealer on it. I forgot to put it on befor the undercoating...doh. The tunnel is about 40" long and 17" across the bottom at the front.
The tunnel doesn't have the be as big as mine is but I wanted to room to work. I made the top flat so that my hvac box would fit above it.
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View attachment 1715032893