The most directly relevant square-port LS heads in this selection are the remanufactured GM 823 assemblies listed for LS3 and L92 applications. Two listings describe similar 823 heads with rocker arms, while the other LS cylinder-head options are 862 or cathedral-port designs and should not be treated as square-port substitutes. Compare casting numbers and engine requirements before buying; the product details provided do not establish fitment for every vehicle or build.
| Product | Port type or casting | Best suited for |
|---|---|---|
| GM LS3/L92 823 Pair | 823 square port | Buyers seeking a pair of remanufactured 823 heads |
| GM LS3/L92 823 Assembly | 823 square port | Buyers comparing a single listed assembly |
| GM 4.8L/5.3L 862 Set | 862; not identified as square port | Buyers whose application calls for the listed 862 design |
| JEGS GM LS Cylinder Head | Cathedral port | Buyers seeking an LS1/LS2/LS6-style port listing |
GM LS3/L92 823 Square-Port Pair
This renewed listing is for a pair of GM LS3/L92 823 square-port cylinder-head assemblies with rocker arms. Its listed reference numbers include 823, 821, 5364, 12600936, 12629062, and 126269064. The seller says the heads are disassembled, cleaned in a hot tank, and pressure-tested to check casting integrity.
Best for: Buyers seeking a pair of remanufactured 823 square-port heads for an application verified to use the listed casting references. The description also says valve seats are replaced as necessary, valve stem seals are new, and valve guides are replaced when necessary.
Check before ordering: “As necessary” means the listing does not promise that every seat or guide is replaced. Confirm casting and engine fitment with the seller or a qualified engine builder.
GM LS3/L92 823 Head With Rockers
This renewed 823 square-port assembly is described for GM LS3 and L92 6.0L/6.2L applications and includes rocker arms. The listed reference numbers are 823, 821, 5364, 12600936, 12629062, and 126269064. The seller describes hot-tank cleaning, pressure testing, new valve stem seals, and conditional valve-seat and valve-guide replacement.
Best for: Buyers comparing a listed 823 assembly with rocker arms rather than a pair listing. Choose this if its quantity and casting references match what your build needs; verify the package contents directly before ordering.
Check before ordering: The product title says “assembly,” but the supplied details do not clearly specify quantity. Do not assume it includes a pair based on the other 823 listing.
GM 4.8L/5.3L 862 Head Set
This renewed listing describes a set of two remanufactured GM LS cylinder heads with rocker arms, naming 862 assemblies and 706 in the title. The seller lists cleaning, pressure testing, new valve stem seals, and valve-seat and guide replacement when necessary.
Best for: Buyers whose engine and build specifically call for the listed 862 head design. It is included as an LS comparison option, not as a confirmed square-port alternative: the product details do not identify these as square-port heads.
Check before ordering: The title mentions both 862 and 706, so clarify the exact castings supplied and confirm compatibility before purchase.
JEGS GM LS Cathedral-Port Head
The JEGS listing identifies this as a GM LS1, LS2, and LS6 cylinder head with a cathedral-port design. Its supplied feature information also names several engine displacements and a 211cc intake specification.
Best for: Buyers looking for a cathedral-port LS head and comparing port styles before selecting components. The listing helps distinguish a different LS head category from the 823 square-port assemblies.
Check before ordering: This is explicitly described as cathedral port, so avoid it if your build requires square-port heads. The feature details provided are limited; verify the exact casting and application.
Buying Guide: How To Choose Square Port LS Heads
Which listing is actually square port?
Among these products, the two 823 listings explicitly identify square-port heads. The 862 listing does not specify port shape, and the JEGS product is explicitly cathedral port. If square ports are required, confirm the casting number and port design rather than relying only on a broad “LS” description.
Should you buy a pair or an assembly?
One 823 product title explicitly says “pair,” while the other says “assembly” without a clear quantity in the provided details. Check the exact number of heads and included rocker arms. This matters when replacing both cylinder heads or matching a partial repair to existing parts.
What should you verify before purchase?
- Match casting numbers and engine application to your build.
- Confirm whether rocker arms are included and how many heads ship.
- Ask what inspection or reconditioning work was actually performed.
- Clarify whether valve seats or guides were replaced; the 823 and 862 descriptions say these are replaced as necessary.
- Have an engine professional confirm compatibility if the build uses modified or mixed components.
Frequently Asked Questions
Are GM 823 heads square port?
The two 823 product listings in this selection identify their heads as square port. Confirm the casting and application before ordering.
Are 862 heads square port?
The supplied 862 listing does not identify its port style. Do not assume it is square port; verify the casting and port design with the seller.
Are cathedral-port heads interchangeable with square-port heads?
They are different port-design categories. The JEGS listing is cathedral port, so it should not be selected as a square-port replacement without application-specific confirmation.
Do the 823 listings include rocker arms?
Both product titles say the assemblies include rocker arms. The pair listing explicitly indicates two heads; confirm quantity for the assembly listing.
What does “valve seats replaced as necessary” mean?
It indicates conditional replacement, not that every valve seat is necessarily new. Ask the seller for details about the specific heads being supplied.