A downhole sub having a first tubular housing with a first internal shoulder, a second tubular housing with a second internal shoulder, and a stabilizer assembly to be disposed between the first and second internal shoulders. The first and second tubular housings are configured to be threaded together, and the stabilizer assembly is configured to engage the first and second internal shoulders. A method of coupling tubular housings in a downhole sub in which a first tubular housing and a second tubular housing are threadably coupled, where the first tubular housing includes a first shoulder and the second tubular housing includes a second shoulder. A sleeve is interlocked with and inside the second tubular housing such that the sleeve is disposed between the first and second shoulders and includes a third shoulder, where the first shoulder is torqued against the third shoulder.