Yeah, Compaq had an all-in-one Cluster kit, called the CL-380. It was essentially a couple of DL-380's with a shared drive array. Now, Compaq no longer sells this model but sells a do-it-yourself kit based on the configuration in the preceding sentence.
Make sure that you get the Windows 5.5 Enterprise and Windows 2000 Advanced server, which give you cluster support. The Standard versions don't come with this.